Overthought has a very good Ultimate Guide to Solving iOS Battery Drain.
Regarding Step 1 I knew that Facebook used a lot of battery, but hadn't thought to disable it's background app refresh and location services. I've just done that will see what happens.
Regarding Step 4 I've never had push email on at all. I know I'm in a situation that not everyone is, but my thought is this: If someone wants to get a hold of me now, they can call or message me. If they're sending email, that means they can wait until I get to it, that's what email is for. If I want to check email, I just open the Mail app and wait a few for second for it to load, it's no big deal. BTW, this is also how I used email on my computer when I was working, it worked just fine.