There is a transition fitting to go from poly pipe to pex. I do not know of one for cpvc. Normally I use male adapters on both the poly pipe and cpvc. I couple the male adapters with a valve or a threaded coupler. On the cpvc male and female adapters, I buy the one with stainless steel threads.
There are multiple coupling systems for pex pipe. For 3/4" and under there are the shark bite push on fittings, no tools required. Pinch clamps that you compress the "ear" on. The tools costs about $30. Crimp rings can be used up to 1", not sure if you can use crimp rings on 1 1/4". You cam buy an apollo crimping tool at Lowes for $80. The premium system is the Upenor proper system. With it you expand the pex, slip it on the fitting, and it shrinks back down. There are hand expander, but most contractors use the Milwaukee proper tools. The M12 tool will do up to 1" and costs around $450. The M18 tool will do up to 1 1/4" and costs around $750. They have another tool for 2" and 3" pex. It costs $2500 or so.
There's is Pex A, B, and I believe type C. Different manufacturing methods. Pex A is the best. It can be expanded 4-6 times its original diameter without splitting. Think freeze resistance.
The one drawback to pex is that it shouldn't be exposed to direst sunlight for over 30 days.