turntable: need some advice on motor etc

Does that make sense ? So what are doing and why ?

No it doesn't in this case. The op stated what is desired and it doesn't really matter if pizza or a dashboard Jesus is on the turn table.

That being said, a servo modified for continuous rotation might be of interest in rotating the turntable. There have been a number of previous post in the forum concerning turntable projects that might have useful info.

https://www.google.com/search?as_q=turntable&as_epq=&as_oq=&as_eq=&as_nlo=&as_nhi=&lr=&cr=&as_qdr=all&as_sitesearch=http%3A%2F%2Fforum.arduino.cc%2Findex&as_occt=any&safe=images&tbs=&as_filetype=&as_rights=