power of 2 question

I'm confused as how I should be using the power of 2s. I've uploaded some 32x32 images which I'll be using with my tiled backgrounds but when I resize the tiled backgrounds to fill the layout how I would like, do I need to keep the resized background in powers of 2 as well?

Also, if I'm using a single pixel and stretching it to fill a specific area, is there any difference between using a tiled background or a sprite for that?

Thank you.

If you mean rescaling in the game: nope, has no effects on memory efficiency with which the sprite is stored, rescaling just costs some computational power, not memory if I am not mistaken.

Second question: don't know.