Hi Kim

Nice to "see" you
Very inventive gym equipment you've got there
As for inclines and speeds, I'd just say try it gradually. If you've never used an incline before, try it at 1-2% a few times before you bump it up. I've never really heard of anyone getting injuries that required more that a rest day or two from overdoing inclines, but if you do have pre-existing knee problems it may be better to take it gradually. If you can walk uphill or up a flight of stairs without getting hurt, I can't see how bumping it up to 5% would hurt you as long as you have good shoes, but take it cautiously if you are concerned.
I'm glad to hear that your weight training is paying off and we've been helpful. Come on and jump into the weekly thread, we don't bite
Mel