1. I have everything on my Lumia 920 and I routinely do 24-36 hrs on it with heavy browsing (twitter + IE), podcast/music streaming and camera+uploads. I think give it a old fashioned battery calibration (use until it drops dead and then charge) and see if that helps. I have noticed a peculiar problem where the battery at times dies rapidly (< 7hrs once) from full charge and I have a strong suspicion that it's WhatsApp. It's just a poorly done app, don't keep it running. A reboot usually helps when this happens.
2. I guess you feel the need to constantly toggle GPS/NFS/Wifi on Android but honestly I have never had to worry about those things eating battery when not used.
3. Hmm the apps angle. I guess this is very subjective and I don't really care for apps which are solely for websites. I can directly browse the websites (BBC in this case).
5. My 920 only every warms up if I do heavy usage (browsing for 15+ mins over LTE, Skype etc.). You might have a bad piece considering this and #1 above. OR you might be using a rogue app eating your battery.
6. Lenses can be accessed from the camera UI (first icon on the toolbar). For panorama, have you tried photosynth or other apps that support panorama? Photosynth is particularly good at "world" (probably the best).