Congrats on the new rifle. I have one and went thru the same problems that you relate regarding the bolt gap and the hard to cock issue. Here is a shortcut to a good CETME site that I use and used to get my CETME to the point that I wanted it to be.
Cetme/HK - Militaryfirearm
Check the back of your bolt or measure it. I suspect it is ground down several thousands - that was Century's way of getting past the bolt gap issue. It should be between 1.834 and 1.837 long. I bought a new bolt (about $20.00 on gunbroker) and put in +4 bolt rollers and brought my gap right on and cured the hard to cock issue.
Read all of the stickys on the site I recommend and they will tell you and show you with vids, everything you need to know and do to your rifle.
Have fun!!!!! I am well pleased with my rifle now - a real boomer when fired but it is fun.
Take care and stay safe.