Audio/Visual Electronics - Need help on my 90 EX...

My stock AM/FM radio and speakers suck in my 90 EX Sedan. I bought another set of 6.5" speakers for the doors and a new headunit. I need some help on how to take the stock stuff out. Any help would be appreciated! Also, how hard would it be to add another set of 6.5" speakers in the rear deck? Looking in the trucnk, it looks like there are round holes already there.

I wouldn't be of any help on this, but I'd recommend referring to a Haynes manual. I used it today to get my dash removed, gotta tell ya I would have broken it otherwise. And they've got pictures too.