1. Is the Gamers Gate downloader needed to run whenever you want to play your games? Only needed when you download and install (so if you keep the backup files, you just run the downloader again to start reinstalling from the local backups)
2. Is the Gamers Gate downloaded DRM; in a sense as Steam always has to run and you cannot use your games without Steam on your system? No. But some games have their own DRM just as if they were retail versions. However, if the DRM involves limited activations, you can ignore the limit as GamersGate will simply issue you a new key if you run out of activations. As they say, once you buy it, its yours.
3. How is Gamers Gate good or bad? I have no real issues with it. Their support is fast and fairly good. And I've only ever needed to contact them once. The download speed is a little slow compared to that of Steam/Impulse though.
4. Does Gamers Gate keep up with patches for their games? It's a bit hit and miss here. While GamersGate do not patch the games, they will sometimes provide links to *ALL* available patches for a game so you can choose which to download and apply. The only time they didn't do this when I wished they had was for Fuel of War -- as that was a real pain to patch. But that's the only time I've had trouble with patching (and think that's partly due to my OS).
5. Do Gamers Gate games have additional DRM attached to the games themselves? Yes, depending on the game. It's basically the same as retail. They don't mention it on the store page, but if you contact their support, they are fairly happy to tell you.
6. Anything else I would need to know but do not know I need to ask? They have regional restrictions, but the restrictions differ to that of Steam, for example. Such as, while I can't buy SEGA games on Steam, I can on GamersGate. Recently, they've had far better deals than Steam has too. I personally find them to be a fairly good service and have used them far more since they dumped their client.
Sometimes, you may have a problems if you are trying to purchase with a credit card as the system they use, PayNova, isn't very good. But using PayPal has never failed me.
Also, while not directly linked on GamersGate, you can find their forum here:
http://forum.paradoxplaza.com/forum/forumdisplay.php?f=332