There are others more knowledgeable than me, but as someone who just purchased a 4002 in the past 6 weeks, I wanted to chime in with my opinion.
1. There are any number of fantastic Beograms to choose from. If you buy a 4002, I am sure you will be delighted, as I am with mine. If you do buy a 4002, you are locking yourself into the older range of cartridges. This may be good, bad, or indifferent, depending on your point of view.
2. The 4002 is very easy to open and access the main board and most all else, even for someone who is "no technician." The 4002 has a few components on the main board known to have issues (see my BG4002 Down! thread), but its reliability and serviceability are both strong points.
3. The stylus is going to be hit and miss anyway. Get it retipped. As for the rest - one school of thought I've seen on this forum is buy something that is cosmetically top notch. Everything else can and will fail, but can be fixed. On the other hand, broken/missing trim, cracked dust covers, etc., is more difficult to fix or hide.
4. Ah - here is the important question. Best to pick up. If that is not an option at all, the most important things are: remove both platters; remove the cartridge; remove the two top plates; fix the tonearm and light assembly up and down and side to side; put thin padding between the dust cover and the table, then fix the dust cover with tape (some also recommend filling the dust cover with peanuts, but that's probably if you don't remove the two top plates; tighten the transport screws on the bottom; wrap unit in bubble wrap; put in box; get a larger box with some packing peanuts; place first box in second box; tape well.
5. No idea, really, and your market is probably significantly different than mine anyway. From what I've read on the forums lately, it sounds like it's a buyer's market these days. Having said all that, one place I watch is Hawthorne Stereo in Seattle, Washington. They are currently selling two both rated 8/10. One is going for US$289, and the other for US$339. I don't know if they include cartridges. Hawthorne's "retail" price for equipment generally runs 25% or so above what you may expect to pay on Ebay.
6. If it were me, I wouldn't pay more than about US$150 (including shipping) for anything without listening to it and seeing it in person. And especially if it were a turntable, I would want to pick it up. Also, have you considered a BG1700 radial deck? I've read a lot of good stuff about the 1700 lately, and I think that will be my next project.
Good luck on your pending purchase!
Current primary listening: SMMC20EN -> BG4002 -> BM4000 -> Beovox M70