I recently purchased a G85 and am using in X. It finally works great after the latest driver update from HP. If you buy the G85, don't use the CD that comes with it to load the drivers, get them from HP's website.
1. Speed isn't great but quality is good.
2. Recently released driver seems to have fixed earlier problems.
3. G85 does both of these.
4. Excellent photo quality when using photo paper to print on. Especially from a machine that's under $400USD.
5. You are right, it's huge. It's replacement, the D135 (I think that's the correct model) is smaller.
The G85 is a workhorse and has been around for a couple of years which is a long time in this industry. One last thing to consider is the cartridges. The reason I went with the G85 is because it uses the full size cartridges, the 45A (it comes with the 45G which is a starter cartridge) and 78A (the 78D is half full). The D135 uses separate print heads and ink cartridges. That kind of scared me because the cost of the ink was about $25 but it only holds about 25ml of ink if I remember right (I could be off base there). The 45A holds 42ml of ink and costs about $30.
Hope that helps.