I hear what you're saying. It can get confusing, with chassis design, but to be fair, the better CS'ed chassis are the ones you CS yourself. Seriously. The D3 is far from and easy chassis to maintain, and it's basic design is overly complicated, so you might find it a pain to have to maintain. I have been into drift for some years, and doing maintenance is just another aspect of it, but something I would have to tear apart almost halfway down, just to clean isn't something I look forward to.
The XI is a perfect candidate for CS. You only have to do some studying on which pulleys require changing, and the belts required. The TA06 won't disappoint, though. As with most things, you get what you pay for.

As far as having two chassis, more IS better, but not to "lend" out, or have anyone else drive. I mean that sincerely. I have learned to just say no, when it comes to people who want to drive my stuff. It removes any bad feelings, because the "borrower" will always refuse to pay for damage. Take my word for it.....your work will not be something you want to see bashed up by someone else.

I go through TQRC almost exclusively, with the occasional order to Tower Hobbies, so I would say to use reputable companies, online. If you can't find the Skyline anywhere, who makes it? If it's HPI body, try and order it directly from HPI international (I don't know if they offer it, but it's worth a look). They sell parts from their website, all the time. I've even ordered parts from their website. If it's not HPI, I really don't know what to tell you, except to wait and check the sites you're likely to use, until they restock the body.

Yah, I've gone through quite a few company's electronics, and have only had bad experiences with Novak. Besides which, their components are not very durable, except their motors. I have no issues with any of their motors, but since their ESC's suck so hard, I don't recommend any of their stuff. I have never had an issue of any kind with LRP, Associated, or Reedy. Some of what they offer can be a bit pricey, but again, you get what you pay for.