They only use a tiny bit of power when not being used for cooking. It's for the clock usually if it has one.
For TVs, and anything with a remote it draws a tiny bit of power for that sensor and the "memory" of settings.

I didn't look it up but I think the ones with the black button must have a fuse in them and so if something trips the fuse - it is only the one in the power strip and not the house fuse.
The black button is a reset button.
just my thinking on it.

I don't think i would buy the cheapest one, i usually get a mid range product. Just my feelings on it.
I think the lowest price ones are mostly for use as a extension cord w/ multi plugs.??

I think you would want some level of surge protection to protect appliances.
some say power strip and some say surge protection.