I dont think I understand the first one. You mean the form isnt avialble to be select after you unlocked it?
Sorry to hear. That certainly sounds odd. All weapons skills are tied to the class level so it should be nearly impossible to lose them if i remember correctly. Could it be that the game changed your class. Also did they maybe come back after gaining one class level?
I havent heard about this bug before. If you like to share it, I could take a look at your save file and see what the problem may be. You save is found under www/ saves. Any file sharing site would work. Here is one possible one https://www.file.io/
Lovely to hear^^ Most bad ends are pretty hidden but there are also just 9. But none is missable. A decent amount of usuful combat abilities comes from side quest and exploration. But some are also gotten through playing the main story.