I'm assuming that given the state that you say your radiator is in and having spent a long time waiting for bolts to 'un-seize' I would say that your best friend is going to be some sort of penetrating oil/spray. I used a combination of WD40 and Plus Gas. (WD40 in a spray can and Plus Gas in liquid form). I put a straw on the end of the Plus Gas can nib to get to hard to reach bolts such as those holding the lower retaining plate to the chassis.
My fan was difficult to prise out of the slots it sits in on the bottom of the radiator so it was good here too. Whenever you're using penetrating stuff, clean the area with a wire brush first to remove dirt and debris so that the liquid actually has a chance to reach the seized areas. When applying the penetrating fluid to a bolt, leave for a few minutes after pouring or spraying it on, tap with a hammer to help the rust seal on it's way to breaking, and use the socket and ratchet of the correct size to turn it the 'wrong way', ie tighten it - not too hard but just enough to crack that rusted seal.
This won't necessarily produce any noticeable effect but I assure you that it works if you persevere. Once you've done this, leave it for a couple of hours, apply more penetrating fluid/spray and repeat the hammer/tightening process. If you rush these steps you're likely to shear the head off the bolts by going at it with brute force. I found this so frustrating but the sense of relief and pride in your work when you get it all back together - with lots of copper grease to prevent this happening again - is great!
I also found a pair of pliers useful for various different jobs, including prising the slots on the bottom of the radiator where the fan sits apart slightly to really get the penetrating fluid working in there.
On my car the lower right ac condenser bolt was just out of reach of my extension bar so I had to get an angle joint to get the socket into the right position to loosen it.
Bear in mind that I found that the fan can come out the top of the engine bay with the bonnet release cable undone but the radiator just has not got enough room to and must slide down out of the bottom of the engine bay with the front of the car jacked up to give enough room to manoeuvre.
Sorry for the long post! Good luck and if you need any advice while you're on the job, give a shout. I'm on the net most of the day today and the next couple of days (for work purposes)! And I'm sure others will be on hand to help.