Sorry for the bugs you've encountered, can you tell me what system you're playing it on? I'll see if I can find a way to replicate them to be able to fix them, especially the save room crash.
The intro song signifies the end of demo, which is why it leads back to the title screen.
I'm not sure why you're only getting 5 CGs but I'll take a look. In the meantime, here's a few things to try: There's an arrow button on the center right of the gallery that will send you to the next page. On day 3 there is also a choice option that if you answer a certain way, it will lead you to find a new CG if you haven't already.
Thank you for taking the time to play the game and thank you for your feedback! I hope I can help improve the experience for you in the future.