About how many accounts you can use. It depends greatly on what you're going to do with each account. If you set all tools to the max and do a lot of posting you will be able to use fewer. If you only do a couple of actions with each account you can use a lot more. It's hard to give an exact number, specs are god so you should be able to use it with a couple hundred, but again, depends a lot of what you're going to do with them.
yes, you can like a specific page/picture