Release it one day late, so donators will get one day early, planned latency.
No you do not have to arrange a meeting but if someone wants to meet with you after donating 50 euros and they want to talk to you deffinitly you should, maybe you can personally talk, guide or give ideas to them.
No you dont have to but there should be social benefit to be a subscriber, for example maybe a steam gift key everymonth, and if someone pass a limit of 1000€ purchase their easter egg could be add in the game like a volcano biome named after them or a random mob spawns after their name.
The key idea is not literally do whatever I said, they are all suggestions but lets not forget main motivation here is to make donation be cool and more interactive with our team, so they don’t feel like others but part of important people in our group. All the examples and brain storms to create this and everything is maybe, and this is probably how I would do it. So basicly donation must feel Cool and give social status.
About mechandise, someone said you guys onto that, is there and post I can read ? Or if there is not lets talk about the idea of selling merchandise, so creating fan base, and gaining their helps will much more easier.