When you start the game, it should ask you if you want to make save data if there isn't already. If you don't, changes and progress you make won't be saved...
The term "ninja'd" refers to when you were about to make a post saying something, but somebody else posted saying the same thing before you. Notably in situations when you're answering a question. You can change your settings to warn you if somebody else posted while making your post.
Normally, you'd get the silent freeze if a single or combination of hacks can't be handled in game. Mostly because of filesize I think. Even just hovering over a specific character in the CSS with a mod over their default costume could make a silent freeze. I'd slow down, and hover over specific characters with colors you know you've modded to try and find out what's causing the freeze. If you can't find it, you can try formating the SD Card
Look at the normal size of the portrait, and take a look at the one you made. Are the sizes for both proportional? If the original size is like... 500 X 500. Is it the same, or proportionally the same? If not, you'll get glitchy textures.
Something you can do is reduce the size of the textures used. Say, the image is 1000 X 1000 Pixels. You can scale it to 500 X 500 Pixels. It'll look more pixelated in game, but it'll reduce your filesize.