There aren't any truly new Quests as such - FEP haven't been manufacturing Quests for a good time now.
Critical Paintball are selling Quests that they are assembling from the stock of spare parts, but they are basically an '07 Quest, upgraded with all the Critical Quest parts.
Now don't get me wrong, these are great marker, with good upgrades, at a brilliant price, and I highly recommend them, but I just think it is worth bearing in mind that you aren't getting a new Quest from FEP, you're getting a Quest assembled from new parts. There have been a few attempts to resurrect the brand, but right now, as a company, FEP do not exist.
The Quests assembled by Critical use the Inoviq board and VX chip.
Yes, assuming no other limiting factors (low LPR pressure for instance, tight bolt fit etc.), then the solenoid would limit the rate of fire. Maximum rate of fire is around 23 or maybe 24bps.