Amy
You will almost certainly find the markings and discolouration are all on the outside of the plastic despite what it looks like from first glance. If so you should be able to do them in place.
Amy
This is real simple, you dont need to replace the lamps.
Get a bottle of Mothers plastic polish and polish the plastic lens, they come up looking like brand new, no scratches or marks.
You can do it by hand or with a buffer.
If they are ever going to squeal they will do it with Bendix pads.
Usually though it is a matter of checking all the backing plate shims and if they look ok you should be able to get an antisqueal grease from Repco or similar.
There is no such thing as a "cheap GTR". What you save on purchase price you will inevitably end up spending on repairs.
Sure there are the odd cheap ones come up when owners are desparate for a sale but for the most part a GOOD GTR comes with a high price tag.
If you are wanting a 32GTR with the intention of doing quite a few mods etc then a cheap one is probably a sensible buy but if you want reliable and trouble free motoring WITHOUT having to fix things then save yourself the time and trouble and pay that little extra for a good one.