A few answers...(maybe)
1. Yes -- although I've been lucky with HIE having loaded it in daylight (shading it with my body) but I've also been unlucky with it being fogged in low-light situations. You only have five rolls -- why take a chance? -- load and unload in total darkness.
2. I couldn't say because I almost never shoot HIE with this filter. In any event, your success with it will depend on bracketing as well, since altitude, time of year, time of day, weather, and location will all be factors. That being said, HIE is HIGH-SPEED film -- great for handholding and shooting subjects you never could with virtually all other infrared films. You can shoot landscapes and other static subjects with other infrared films -- try using HIE with a red 25 or 29 and shoot people and/or moving subjects and/or places you can't set up a tripod.
3. Sorry, don't use HC110.