Yes all the stuff you've mentioned is physically interchangeable. The only real issue is if you want facelift rear lights you also need the bumper etc and to reprogram the light module or you can get them to work with a bit of a rewire . Pre to post halogens are plug and play, Xenons arent so easy (flash to pass is the issue) but can be made to work with a post facelift light module or a bit of a rewire/coding a few options etc. Adding cruise/heated seats is easier on pre 09/04 cars as they have the wiring looms in situ. After that date you have to add the wiring looms which complicates things. Think that's about it, but I'm sure others will point out anything I've missed