Shower/bath diverter valve

[TapTight]

I have a leaking shower and want to replace the diverter valve and shower mixer but am slightly confused as to the valve set up.
The diverter feeds the shower, bath spout and an additional shower on a hose, (3 feeds) what kind of diverter do I need to buy?
The current shower mixer turns the water on and off and adjusts the temperature, again what should I buy?
Last question, what is the pipe configuration into the diverter???

 

[Puddle]

Is this a case of do not know what the problem is,so replace everything or do you just want to replace everything for new,if so just buy what you like as long as it is good to use on whatever plumbing system you have,not doubt you will have to change pipework anyway
If you just want to repair leak,do you know make,get service kit for on/off valve