Ratcheting noise at end of travel is normal although if adjusted right, they may not do it when retracting fully.
Gaps are probably and adjusment thing. I would make the sides equal and then make minor adjustments unitl everything is fairly even. Then adjust so the slide retracts a little more. Play with the adjustments to get it right. It really isn't all that complicated and it would be hard to damage anything. I've played with them quite a bit - even on my new trailer. I got it to work better than the factory with just a little experimentation.
Sqealing - Mine did the same thing really bad. Dealer said they all do it and nothing can be done. Pure baloney! I had my wife run the slide in and out while I looked and felt the parts under the RV. The noise is caused by the rubber rollers which are mounted on the smooth section of a simple bolt. The bolt acts as an axle and rubber against metal is going to squeak!
You can see the 2 rubber wheels behind the small gear. Use a jack and some wood to take the weight of the slide off the wheels and remove the bolt/axle. Lube it with some silcone based grease and put it back together. Plumbers grease is the same thing.
Mine was dead quiet after lubing.