Congrats!
I have a 511 Eotech - the one with the N Batteries. They are supposed to last 200 hours, but I wonder if that isn't marketing hype. Maybe that is at the lowest setting. I've had my PS90 about 4 months. My Eotech batteries only lasted 3. I had only made 3 range trips. Admittedly, I played with it around the house. So, there was several on and off times. But AT MOST, I had it on MAYBE 25-30 hours.
Now, it was the batteries that came with the unit. So, maybe my new ones will last longer - we'll see.
The PS90 rail isn't that big - which is why I chose the N battery version. But, I think U should get the 512 - Revision "F" - that model lets U use lithium AA batteries. The claim is up to 1100 hours of use. U probably won't get quite that much - but it is more than the N battery version.
I figured that I'd only have to change my batteries 1x a year - just to play it safe. I'll see if I get longer than a 3 month interval this time.
I've seen others speculate that maybe the Eotech draws a little current all the time - even when off. I wonder about this now.
As for the sling - I have the single point from URBAN ERT, and I love it. He does have a 2 point sling that attaches to the receiver. I would avoid any slings that attach to the barrel. When firing, U don't want anything pushing or pulling on the barrel.
