As another senior on a fixed income, let me say this; Just spend the money to get a good one. Ron's Tools is where I got mine. Yes, they are spendy, but the aggravation of trying to work with cheap crappy tools is just not worth it.
We feed ravens and bald eagles. We get meat scraps and fat from a butcher for our sled dogs. Anything that gets rejected for the dogs goes down on the lower end of our property and the birds are circling before we can get it unloaded.
The lever opens the jaws. It is made such that the jaws are in a closed position until levered open. Pull down on the handle and the cam will force the jaws apart.
I assume you are catching the first thread with the second needle. Two ways to deal with that. 1; Pull the first thread tight and against the side of the hole before inserting the second needle. 2; Insert BOTH needles and pull first one then the other. #2 is the way the oldtimers at my local saddle shop taught me.
Any time I stitch, I never use more thread than I can span, arms spread out. I generally overstitch 3-4 stitches. Trying to use more thread than that is a huge PITA, and slows things down.
Had you said they were sheepskins to begin with I would have told you there is a 98% probability that they were tanned. 'Fur rugs' generally refers to bear skins, cougars, etc.