Good questions
I also think this depends on many factors. As you are asking for personal opinion, please take what I am going to say as only my own way to deal with those.
I would love a long term arrangement but would not offer it to anyone. Even lovers I absolutely enjoy spending time with are not always good candidates for that kind of arrangement. Let me explain. I would only have one of those with people that are seeing me as a ''side dish'' and not as their ''main dish'' lol. For exemple, I could offer exclusivity and have a bank of hours they could arrange as they want in my schedule. I would make myself available all month, not plan anything away from MTL, but would not be 24/24 with them all month.
Exemple: One month arrangement. We plan a weekend together, then two mornings one week, one full day next week, two overnights and a duo the last week. I don't see any other lovers and text every day.
Exemple I will never do: Go away one full month with a client oversea and be 24h ''on''.
Why? I would become so angry hahaha I need my me time to be my 100% with my lovers and time to recharge. I can get cranky if I'm social for too long and that would be a bad experience for everyone involves.
As for the money asked, I would ask for something that covers my expenses for the month as well as something that I feel worth the work involved. Mainly staying available and missing on social opportunities for exemple. I might miss birthdays or parties because of this arrangement. So between 5k and 15k for a month of exclusivity (depending on the amount of physical time asked).