Incompatible save files is something that has happened once, due to the addition of a large plugin (the map stuffs). In the future it isnt very likely to happen again, but I don't want to promise that. As for the time frame in which the game will be finished, I'm not entirely sure, The game is being made by 2 people (me and my partner who wants to stay mostly anonymous). Usually what I always say is when making games to take your projected time and double it, but things have been so chaotic and our straights so dire that I can't exactly in good faith say when, sorry.
As for the egg thing, It's an issue I'm aware of and totally not intended lmao, I'm gonna have to fix that one soon, I had mentioned earlier today that I plan on doing a full revamp of that system.
Glad you like the game though!