How many times per second/minute a miner retrieves a new block template with the newest list of transactions from ckpool?
Not ckpool distributes the block template actively, instead the miner has to call it from bitcoin daemon with get_transactions or get_txnhashes – so at the end the interval depends of the mining firmware, right?!
Referring to this, are there big differences when I use a Newpac with CGminer or a S9 with Braiins or Bitmain as mining-software?
No, I set the interval and they are pushed out to miners regularly at 60 seconds here. You can't control this at the client end.