You underestimate how many bugs are in the game. The dev wants them all fixed, now matter how small of a possibility those have to happen. This together with the fact that for a "3D" game you need more "content" then you need for a "2D" Game makes it reasonable for me, why he gave himself that much of a time window.
If you played demo 3 (page 25, CrazyMega01 has a download link posted there) then no, there is no new one.
After defeating the Succubus Lilie Mimie, you need to go back to "The Forest Witch Home". TP there, then go left. There you can talk to Mimie who gives you the option to refight the bosses. Don`t know actually if you need to beat the game for this, now that i think about this, but you will find out soon enough.
What you mean? Your character is invisible?
In my experience the simplest fix for me for problems like this has been opening the game with mtool and then pressing GOTO:map or teleporting etc. and it fixes the issue (This is for RPGM games). Not sure which engine this game runs on but there is probably an invisiblity flag or something that got triggered by accident. Once I got stuck facing one way in a game and I figured out that it somehow enabled a flag that fixed my direction and didn't let me turn so I had to turn that off manually (using mtool). Maybe this will work for you.
You mean from Flower Stella?
after beating squid pirate queen, and doing something (cant remember what, sorry :\) she lets you go to an "infinite" dungeon, after doing 50 or so floors without saving (halves your progress if i remember correctly) you can fight that boss...
Have you tried double clicking on it or right clicking and then pressing open?
