Hue bulb without Hue Bridge?

I just got my first Philips Hue light; one of the Friends of Hue: Iris fixtures.
I don’t have a hub/bridge yet (it’s just connected directly; and I know about the reset needing a remote, etc), and I have some related questions…

  • Is there both a Hub and a Bridge, or are these just two words for the same thing?

  • Which Gen Hub?
    I could buy a Gen1 hub from a guy I know for cheap. Why or why not to buy it?

  • Wimpy Purple?
    Has anyone else noticed that purple is so wimpy on these things, or did I get a dud?

  • ST Mobile App Doesn’t Save Last State
    Every time I go away fro this device in the ST mobile app, and come back, at least two of the settings for the device in the app change. First off, with it connected directly to ST (no hub/bridge), in the ST Mobile App there are 4 things I can adjust…

  1. On/Off
  2. Brightness
  3. Color Hue
  4. Color Saturation

When I leave and come back, it appears as though the ST mobile app saves the state of the first two settings, but not the other two. So, if I want to adjust the other two, I need to change them to something else first, and then change it back to what I had it set to previously and make adjustments from there.

Is this just because of the fact that I have it connected directly to ST, and is this accounted for and taken care of while using them with an actual Hue hub/bridge?