Hello Bob and welcome to the TD 160/ 150 world. These are highly tweakable turntables--I've been experimenting with my TD 150 for about seven years now, and it's still teaching me things
If you haven't already explored the pages at theanalogdept.com web site, you'll find a wealth of information about virtually all models of Thorens turntables.
Mats. Your mat preferences might change as you try multiple mats and as you combine mat choice with other changes in your system. It's inexpensive and fun. I made cork, cork with cork spots, cork with foam/cork spots, paper mat with cork spots, diy ringmat, foam/cork spots on the bare platter, and wool felt. I liked all of them better than the stock rubber mat (which isn't bad), and of those I liked the wool felt best. The only commercial mat I tried is the Herbie's Way Excellent mat and that's the one I've stayed with.
LP weight...after experimenting with a weight + most of the mats above I liked the presentation without the weight when using my two favorite mats (woof felt, Herbie's). I don't think the bearing would be damaged by using a weight, but make sure you're using a good quality oil in the bearing well. I'd imagine that whatever wear takes place with the platter bearing over time would escalate with a weight, but I have no idea how much or if it would matter. Never tried a clamp, for the reason you mention.
I've played at least a few thousand LPs on my TD 150 and can't remember running into one that was impossibly tight on the oversized spindle. Not yet anyway. It hasn't been a problem, but it is an occasional annoyance for me...
Hope this helps.