"What you need" contains a wrong part.

I try with crucial 2x16GB and corsair 2x32GB they are labled as mac memory. Owc is good choce too.

Like first comment I made a mistake and my iMac not started .Re assembled it again 15 times changing ram in one place to other, old one, new one.Only original moduls working and top one .At last it was that slot near pcb was to tide and ram partly fitted. Even it locks at place needed some force to get inside. Finlay started and everything is ok. Just you may advise to look how deep is module inserted in slot.

What type of thermal pad is used between ram modules?

The battery is SP332230AB with the following dimensions :

Length: Approx. 28.5mm - Width: 20.09mm - Depth. 3.07mm

You can find some on ebay.