Upgrade Advice (HEQ5)

[deadsimple (Ash)]

Hi all. I've been using a new 8" f/6 Dobsonian (from Bintel) for a couple of weeks now for observing and planetary webcam imaging with some success. I find the mount extremely frustrating for imaging and would like to work out a good upgrade path for both the short and long-term. I hope I'm not asking too many questions:

-Short term-

1. Would a standard dual-axis-driven HEQ5 mount right now be a good move for the 8" ? Andrews has it for $800, and I don't think I could afford a $1500 EQ6 (which I would have preferred). Any alternatives? The HEQ5 just seemed like the safe bet.

2. What sized scopes would that handle well? I've heard 8" Newt is fine, 10" is pushing it and 12" is crazy talk. Is 2/3 the rated weight recommended or is loading it to 100% rated load fine in the real world?

3. Would I just need to acquire a mounting plate and tube rings to get a HEQ5 up and running? Anything else worth knowing?

-Long term-

Later down the track I'd be wanting to get a better telescope. At this stage I find the 8" Newt OTA big enough, so I don't see myself moving to a 10 or 12" Newt - portability and quick cooling are as important to me as aperture now. I see the C9.25 and C11 SCTs seem to be popular among the photographers, does anyone have advice on these models (in any context)? Any alternatives? No problems on a HEQ5, etc?

Thanks!