Time for a new stereo system in 123 wagon

I have done a couple of searchs and I have gotten a lot of good info, so I'm going to post my thougts to see if you guys think it will work.

This is for my 123 wagon, the head unit has finally died, and it has stock speakers.

I'm thinking about the Sony CDXF5505X radio head unit. What we like is it plays mp3s and is xm radio ready. Oh and it is cheap 189.00 at cruchfield which claims it will fit my car.

For speakers I was thinking about Sony XS-W4021, cruchfield claims they will fit and are 4" speakers, I thinking about using them for the front and the back.

Additionally I was thinking about adding some small sub in the hatch of the wagon. I think the I can fit and 8" in this is the on I was thinking about Rockford Fosgate P18S4, but I will need a small amp to drive it. which will not be a big deal.

any thoughts?