ok im 200ish lbs 6 foot i just bought a Torker lx 20 inch cause i thought i might want to hop around a bit like you kids do. its been 100 years since ive been on one.
question is: am i just gonna break this thing the first day, should i have spent the extra $$$$ for a fancy trials uni and does it hurt more to fall when your 45than it did at 16??? I really just plan on bouncing around my yard, making a couple obstacles to hop up on etc…
You are going to trash that thing in no time. The only thing I would practice on the LX is freestyle tricks (e.g., one-foot riding, wheel walking) if you want to keep it rideable. If you want to do hops and the like then you’re going to need a unicycle with splined hub, something like this. I’d also recommend upgrading to KH Moment cranks so you don’t have to worry about replacing your cranks in the future. If you’re really looking to pinch pennies, this uni would also work, although the skinnier tire makes hopping around a bit more difficult, and you’d have to upgrade to the Moment cranks on that one because the Qu-Ax cranks will not last too long. The Nimbus trials with Moments would be a great beginner’s trial uni and would hold up for quite a while if properly maintained, so that would be my recommendation.
I’ll leave it to somewhere a bit older than me to answer your last question, even though I’m pretty sure you know what the answer is. 
Nope, falling at 45 aint the same as falling at 16. But that doesn’t mean you can’t do it successfully. By that I mean falling is simply going to happen in this sport at any age or skill level. Obviously, the trick is getting back up.
Get some trials style shin/knee guards and a good helmet. I also suggest wrist guards and gloves. If you really want to feel invincible you can also get baseball sliding pants, which have padding for your hips. The bottom line is accept the fact that you are going to fall. The less afraid you are of falling the more at ease you will be and the more fun you will have.
After your skills and confidence in those skills improve you can start backing off of the less important safety gear. It also helps tremendously if you know how to fall properly, i.e., rolling out of fall instead of going splat. I had a rider tell me the other day that if I had video of all my falls I’d be a hit on YouTube!