Braab8, I don't recall calling the VPI tables "thick and heavy", but it may apply a little, especially in the MkIV and below. Many suspension TT's sound a little like that in the bottom end. The Linn is like that.
Your questions relate to the order of importance of items in the analog chain. That order is TT(bearing,platter,drive), then tonearm, then cartridge. Improving an item down the chain, when the items up the chain are not maximized, does not yield the maximum performance increase you paid for. For example, if you paid $1k for a cartridge, and $1k for a bearing/platter upgrade, the bearing/platter upgrade would sound better with your old cartridge than the $1k cartridge would sound with the old bearing/platter. This is because the improved bearing/platter assembly allows the old cartridge to perform at a higher level than it previously could. The new cart on the old platter would maybe sound smoother and prettier, but musically no better(assuming your old cart was any good at all). Same with the tonearm. You can get more benefit from upgrading the tonearm than from upgrading the cart. This is not to say that you should have a crappy cart, but until you have a top level TT, you are not getting what the great cart could offer anyway. So that is the basic way of doing things in an analog system.
Ok, now the cart issue. I like the 10x4 MkII, in the Dynavector line. It is real good, and reasonably priced. It is a good price/performance cart for your TT.
Referring to the guidelines above, I would say that if you are going to spend more money than that, get the MKIV upgrade, or move even higher in TT's. If you want to stay in the VPI line, the TNT will sound better with the SME 3009, than a Graham 2.2 on your MKII.(Being similar expenditures). The costs might not be what you are considering but the logic holds at any price point, assuming true performance improvement for the money spent.
The Origin Live Silver Tonearm is not a RB250, nor the same as a OL modified RB250. It uses a RB250 mounting base, and that is all. The tonearm tube, headshell, bearings, bearing locations, counterweight, end stub, wiring, are all Origin Live product. This is not a Rega arm. It sounds considerably better than a fully OL modded RB250. It competes with arms costing as much as 4x its cost. An excellent value, and a must for anyone assembling a high performance analog rig on a medium budget. It is especially good if you are considering low compliance cartridges, since I don't think that the high end unipivots do as well with low compliance as they do with high compliance.
I think that if you think over what I have said here, you will know which avenue will give you the best results for your money. If I were you, I'd get a reasonable cartridge and move quickly up the TT line. Once you are at the TNT level, then you can think about these other options. Don't forget about the Teres TT. It is alot cheaper than a TNT and will do at least as well.