Hi,
Go for 6 SE, it will sound brilliant. The 8 SE IS better, but they are both superlative. What's great about going down the Cyrus route is if you get the 6 SE and after a year or so, feel that you want a change, you can send your machine back to Cyrus and have it upgraded to the 8 SE and once that's done, if you want even more, you can add a PSX-R.
Sorry, I can't be of much use on the standmount recommendations.
Cyrus upgrades cost an arm and a leg. You'd be better off flogging the old unit on eBay and buying a brand new 8-SE. I think (emphasise my opinion) the "upgrade" spiel is more of a marketing ploy than an actual desire by Cyrus so-to-do. About the only things salvaged from the "upgrade" are likely to be the case and the power supply, maybe the loading mechanism, but that's about it.
Go for the 8SE straight off the bat.
As for the PSX-R route, better bet, if your speakers are bi-wireable, would be to add an 8-Power or even X-power and bi-amp first. Pick up second hand PSX-Rs on eBay at half the new price as and when they come up and as and when you have the cash to spare. It's basically just a transformer after all, with no moving parts to go wrong. I bought three of my five PSX-Rs that way.
Me? CD-XTSE and DAC-X feed PreVS2 feeding 2 x 8-Powers in twin mono mode. All with PSX-Rs.
I should be sponsored by Cyrus and Chord (and B&Q)!!