when mercs lvl to 20 lvl you upgrade them and he is stronger and then you can upgrade them on lvl 50, 80 and 100.
you need ashen crystals to upgrade merc and it change mercs look, name and stats
Guilds dont fight for town, there is some type of auctions where you bet your guild points, and to get get guild points you need to do guild missions which you get from menager scrolls, there are others ways to get guild points but dont know em.
So far the guild max is 40 players per guild, maybe it can go higher, dont know.
Craftin and weapon upgrading in this game is fun cause nothing seems to fail, It is not that easy but it dont fail, it is only a bit expensive but it ok, and when you wonna craft something it has craftin points and you get those by winnin battles against mobs.