The template I made up is like a flowchart - look at the bold on the left...that's the entry point into further settings that are to the right, and any bolded entries that are to the right are still under the main setting, just a different setting or series of settings.
i.e.
Wireless & Networks > Airplane Mode
Wireless & Networks > WiFi
Wireless & Networks > Bluetooth
then
Wireless Networks > Mobile Networks > Network Mode
Wireless Networks > Mobile Networks > System Select
...it was just easier to draw up a flowchart that reads from left to right (the template) than to type everything out long-form like I just did here.
As for 4G, I'm not in a 4G area... in fact, the closest 4G area is about 250 miles away, but I will say these things: I have computers for downloading. I have 30MB/s downloads and 5MB/s uploads, so it's better than 4G, and it's on my 2 X 30" monitors that I can see just fine!
Also, about leaving 3G on, or GPS on/off or whatever - that's all trial and error for each individual phone and individual ROMs. I found back in the olden days when the D1 first started getting ROMs, that some ROMs would behave better (and get better battery life) if you left GPS on and data off, where other ROMs didn't like either of them turned on - or vice versa.
I've had the best battery life on my Bionic (stock but rooted) with GPS Standalone on all the time, Background Data turned off unless I need Market for something, and WiFi on when I'm near an access point. That's my own trial and error and may or may not reflect the best set of circumstances and settings for everyone.
For me, I will say that since I don't use my phone as a computer, I have no need to have data with few exceptions - I run 2 computer repair companies, and sometimes when I'm out on a housecall, I have to transfer data from my server to a client computer that has no internet access, or sometimes I have to use WiFi on my phone to determine exactly which access point has failed at one of the hotels I take care of (WiFi Analyzer FTW!).
Anyway, my point here is that I don't use this little computer as a computer except for when I absolutely NEED it, and that's where most of my great battery life comes from.