Need a vacuum pump. Something that you can hook to the low side pressure fitting, and draw a vacuum on the system. A rather esoteric tool, unless you can cobble one together. Another alternative would be to take it to a shop, and have THEM draw a vacuum on it for you, then, you just do the rest.
I think advertised capacity of the system is like 2.2 pounds of refrigerant, or something. Should be a sticker under the hood that will tell you. Get a bit more than you think you are really gonna need, as you can never completely empty the can into the system. (get at least one of the cans that comes with a gauge.)
Changing the compressor will be easy. One electrical connection, one connection for the lines. (I think there is only one, two lines, joined??) and four bolts. (don't forget to take the belt off....
) Make sure the system is empty before you crack it open..... Then, just swap the compressor, replace the other parts... (orfice tube is supposedly not serviceable.... might have to check service manual for location..... also, you will need the quick disconnect tool for the a/c lines....) Once you have it all nicely reassembled, take it to get a vacuum job.... and if that holds, add refrig. to the correct pressure for ambient temp. Should be golden.