itch.io

No, there is only a demo and this game not have enough content to make it fully free, game can be bought only on DLSite or you can play in full version if you subscribes at my patreon to the "swordsman" tier

Yes, game have it

What happened? I can't answer here frequently, so I write here link to newground version, at newgrounds I answering often, you can try to download and launch game from *.exe instead of browser version, also try to reload from last save it can solve some problems, or if it stuck at some point of fighting, then welp... try to grind hard and increase attack power and just 1-3 hits her, it can work with every boss (except empress, for her you better to have a lots of hp and lots of your react)

Yes, only for patrons, but anyway I see that here is not much people at itch.io, so I can left it here link