Alright, I'll do the landlord (I'm French). I'm always quite amazed at the amount of stuff people send without asking them to, usually a lot more than what the law allows me to ask... The main risk for you is someone putting a nice fake classified, gathering your documents, and then using them for identity theft.
Therefore, a good middle ground is to send document scans, but blank part of the vital information on the documents that are most likely to be used for identity fraud, like your ID card's serial number.
For the pay slip, it'll be a bit more difficult. I usually only ask for it when signing the lease, but if you're dealing with an intermediate or realtor, they may not want to meet without having a complete file.
What you can do is write a summary with all the information, and add "I'll bring all documents when we meet."
The purpose of all these documents is mostly to prove how much you earn. For example if you don't pay the rent and I sue you, and I can't produce proof that you could actually pay the rent, the judge will tell me "so what? you did business with this guy without checking he could pay? you have no case, bye bye." That's completely absurd, but it is legal precedent and I've seen it happen. So, no pay slip, no business for you!...
The city I live in is having a housing crisis (as declared by the mayor). I think many landlords take advantage of this.
Hehe. Actually, it's very simple. Since any candidate who makes more than the one I choose can sue me for discrimination, my only way to avoid problems is to pick the richest one. Ahhh, socialism...
I don’t feel comfortable giving all this out to a stranger before I even have their phone number, let alone viewed the home.
Well, the problem you have is that other candidates will comply so they will get the deal.
Also do you really think I'm gonna hop into my car and drive 20 km to the place for a visit before even knowing you can pay the rent? People commonly ask "can I visit" as first question, however they have no clue.
Some building managers don't care and just say "yes". This results in 50 people waiting in line in the stairs for 2 hours while clutching their thick files to visit a tiny appartment (this is common in Paris). That's just disrespectful IMO. I prefer to pick based on documents and only do like 5 visits or less. This results in much less hassle for everyone involved.
In fact, if the first thing you ask is "can I visit" and they say yes without asking any questions, expect either a group tour with a huge crowd, or something is wrong with the house and they need the maximum amount of visitors to find a sucker who will rent anyway (for example, there's no thermal insulation, or lots of noise, etc).
One time I got a call from a private number saying that I had applied to his rental the other day. He asked a lot of rather invasive questions, like wanting to know the address of where I worked and where I was from.
Yup, I always ask where they work. There is a simple reason: some tenants are new to the city, and they don't know the public transport infrastructure. Quite often, it turns out that they would have to switch lines twice and this would result in a very long trip time. Or if they use a car, they would have to go through a famously jampacked road. In such cases they are much better off looking in another neighborhood.
I don’t really feel comfortable telling this to someone I don’t know.
Well, suck it up, you're gonna have to do it. Just list the stuff that can be used in identity fraud and blank some digits. You'll be fine.
I get a lot of spam phone calls
I no longer put the phone number in listings because I get too many spam phone calls from real estate "professionals" too. Email is more convenient as it allows all the information to be neatly sorted.
and ask that the person first replies with a text so I know who it is and can answer the call.
Texts are inconvenient, don't ask for texts, you'll just get ghosted.
Just today I went to view a home and the first thing the landlord does is asks to see my ID. She then quickly takes out her phone and takes a picture of it. This is actually illegal
Come with a copy of your ID and give the copy (with the numbers blanked). If they ask, say it's about identity theft. Can't argue against that.
Also did you meet the landlord, or an intermediate? In the latter case she needs proof you visited so she can claim her commission even if you go direct with the landlord and squeeze her out of the deal...
If the listing is from a "professional" then you can use a reverse directory and check their phone number corresponds to the proper business name. Pros will usually have a link to their website, and you can google the name and add "scam". You can also ask for more photos of the house to ensure it's real. But if it's an individual house they may not tell you the address, because you'd just go there and they wouldn't get their commission. If they do tell you the address, check on google street view.
I hate it when I reply to an add to only be given "please a give self-bio, your employers phone number, if you’re single etc."
Send the information you want. If there's enough in there, they won't ask for more. Honestly I wonder why they ask for the employer's phone number.
self biography, what I do for work, address of where I work, how long I worked there
File under "prove you can pay the rent", you won't be able to dodge this. If you want to increase your chances, mention why you like the place. For example I like a tenant who works very close, because they'll be happier and stay longer.
where I currently lived and how long I lived there, references
I never bother asking for this, but if you were in good terms with your previous landlord, it doesn't cost you anything to add a reference.
ID such as driver's license
See above, ID is required to sign lease, but before that a censored copy should be just fine. I wouldn't mind.
sleep schedule, eating habits, how much time I spend at home, sexual orientation
All illegal for a landlord to ask here (France) so no need to answer, esp. sexual orientation, who cares? HOWEVER if the classified is from roommates looking for a new roommate, YMMV, sleep schedule would make sense for example. Whether roommates have the right to ask about sexual orientation is... an interesting legal question.
where I'm from
If you're a foreigner then you will need proper documents to show you're legal so your nationality is relevant. YMMV depending on legislation. For example here, not doing business with someone who doesn't speak French is discrimination and thus illegal, but that doesn't solve the problem of how they're going to read and understand the contracts! It's a can of worms. Last time I had a dude who spoke only Japanese, with his Chinese GF translating into English. We managed... it was fun!
if you’re single
Your relationship status is irrelevant but there is a legit question hidden in there: the landlord will want to know if you're looking for a flat for yourself, or youself+partner+kids, roommates, etc, as the leases and legal status aren't necessarily the same. Also if you have a partner you have to decide if they'll be on the lease or not, if so then you'd have to tell. If you have a partner who doesn't live with you then no need to tell. Here the legal thing is that if your partner's primary residence is with you then some details like insurance (and who actually pays the rent) have to be sorted out.