Normally, if a group of friends want to play poker together, they play for money, but only for very small amounts. The whole point of playing poker is that there is something to loose, so people think before betting. If you can always get as many new chips as you want for free, you may as well bet everything, every time. So you either have to play for something (money) or you need to limit the amount of chips people can get, and don't let them play anymore when they are gone. Doing something together with friends is not so much fun if half the people are not allowed to play anymore, so that is why people usually play for money.
On the other hand, nobody wants to loose their rent money on a game, nobody wants arguments, and most people don't want to make money off their friends, especially if they play a little better than the rest. So people usually play for very small amounts. For me, a general rule of thumb would be that even if you are extremely unlucky, you would still spend less than what you normally spend on an activity together. On average it costs nothing of course.
When I was a student I would play poker with my friends about once a month. If we went out for a few beers I would spend 10 to 50 euro most nights, if we played poker together, we would have a €5 buy-in. That would normally give me enough chips to play for 1 or 2 hours on a bad day. On a good day I would obviously play all evening with it because my pile would only grow. The most I ever lost was €20, and I also won €15 to €20 a few times.
In your question you are not clear about whether you want to play for money at all, and if so, for how much. I think that they will tell you that they want to play for very small amounts if you ask them. I would think about whether I am ok with that before I ask the question. If you tell them you don't want to play for any money, they can consider changing the plan for you, if they don't want to change the plan, at least they know whether they should count on you. If they tell you they want to play for a completely insignificant amount, and you tell them that you still don't know if you want to join, they can't do anything, and it is just annoying for them.
The second issue you brought up is that playing for money could lead to arguments, In my experience that is very rare if you play for very small amounts. The only thing I ever saw that caused some irritation is 'borrowing from the pot', of from the winner. People want to buy more chips, but they don't have the money on them, so they get the chips anyway, and promise to pay the €5 to the winner later. What often happened is that the winner does not want to make money off his friends, and tells the people to forget about the money that should still be paid. This is for fair to the people who did bother to come prepared, and went the extra mile to get some cash, they get a bit annoyed, and may forget to bring money on purpose next time. Then things get messy, that is why we did not allow borrowing from the pot anymore after a while, and told people to borrow directly from a friend if they don't have the money on them, that worked fine. Nobody was ever annoyed for long though. Often the winner would take back his own €5, and spend the rest of his winnings on some beer for the group. The annoyed people had 3 hours of fun for only €5, and they they even got back 4 of them in beer, so they forgot about it not being fair after about 10 seconds!
I always had a lot of fun playing poker with friends, and in the end it was one of the cheapest activities we could do, so I can only recommend it, but only if the stakes are low and you wont miss the money you could loose.