Push Ups, Dips or Handstand Push Ups

I have a few questions about conditioning.

What do you do for pushing strength? 
You can do Push Ups, Dips and Handstand Push Ups. Do you work all 3? Does one relate to the other?
What works what?

What do you do for back strength?
Do you work weighted Reverse Sit-Ups and Leg Lifts? Or only arch rocks?

Thanks!

If strenght is your goal then you cant do all 3 and progress well as you would if you do only the hardest one of those 3. If somebody can do handstand pushup then normal pushups and dips would be to easy for him and he would use it as a warmup. I curently do tuck planche pushups and wall assisted handstand pushups (belly to wall) and i use pushups as a warmup. Pushups should be mastered first, then dips and then handstand pushups. Dips work more on pecs, handstand pushups more on shoulders and pushups work on all pushing muscles the same in my oppinion.

For lower back i do arch body rocks, arch body holds and sometimes reverse leg lifts.

Thanks guys! My girls can do probably 30-35 push ups max and 10-12 dips max. I don't know if I should keep the dips or switch to handstand push ups. 

Same for the arch rocks. They can do tons of arch rocks, obviously and I wondered if it wouldn't be wiser to switch to a harder exercise like the reverse leg lift.

Ahh sorry, and what about elevated push ups? Like putting your feet about hip height and perform normal push ups?