Shower Diverter / Leak Problem

I have a 3 valve setup in my shower (hot/cold/diverter). Recently I had felt the handles feeling kind of loose and I had been having to turn them more in order to shut off the water. Even then I would have a small drip coming out of the faucet, which continues. Also, when using the shower a steady stream of hot water flows out of the faucet . Eventually I broke off the handle on the diverter. Went to OSH and bought a generic replacement kit. The one with the square rubber adaptors that connect the base of the handle to the stem. I used the best fitting adaptor, but when turning the handle the adaptor would slip causing the handle to turn round and round without anything happening. I ended up using the handle from the kit but keeping the original base which connects to the stem. Everything seems to fit fine. I get regular water pressure out of the faucet, but when I turn the diverter (which feels normal) I get very low water pressure and volume coming out of the shower head. It seems like only a certain amount of water is allowed to make it to the shower head because I'll turn both the hot and cold handles round and round and the same amount of water will come out. The only thing that changes is the temperature based on which handle I turn.

Sorry for the long explanation. I am brand new at handywork. I would so greatly appreciate help with:
1-Fixing the water pressure issue (urgent)
2-Fixing the faucet water flow while using shower head
3-Fixing drip

Thanks so much!

For numbers 1 and 2: You should have just bought a new diverter handle and diverter stem to replace the broken ones, and all your diverter problems would have been solved. The new handle and stem need to be exactly the same as the old ones.

For number 3: You need to replace the rubber washers located at the bottom of the hot and cold stems in order to stop your leak.