Thanks for all of these points.  I ceiling mounted the projector over the weekend.  The mount is one where you can dismount the projector pretty easily (loosen 4 hex screws) in case of bad weather, crazy temperatures, whatever.  I also mounted the screen to the wall.  I built the screen myself, very cheaply, from basic 1x4 lumber and some cheap white "blackout screen" material from the local fabrics store (seriously, like $50 in materials and an hour one afternoon with a staple gun).  Trust me, this won't be a THX certified theater by any means. 
This brings me to my (current) projector.  It's old.  Like really old.  It was state of the art when new, but it's like 15 years old now - I purchased it for cheap from an office liquidation sale.  It's an old NEC, but the lamp is rated for 2000 hours and only has about ~600 on it.  Max resolution is 1024x768 (
XGA, and also only 4x3 ratio).  It also doesn't have an HDMI input, only VGA (and s-video, but I won't be using that).  Like I said, not THX certified.  That said, I'll eventually get a new projector when this one craps out totally, assuming that the family and I actually use it a lot (and I imagine we will, my 2 year old will love watch moving on it I'm sure). 
So all of that brings me to the point, sort of a question.  I tested the projector with a simple 
HDMI -> VGA cord this weekend, connected to my laptop, and it got picture (though it altered the resolution and aspect ratio of the laptop).  Brought up netflix and watched about 10 minutes of an episode of Parks and Rec while fine tuning the picture and screen locations.  So it works, at least with a very local source with a 6' cord.  So now the wiring question.  I think I'm going to attempt 
these (hdmi extenders over cat5).  Simple, cheap, and they don't need to be plugged in) and I already have plenty of cat5e cable in a box.  That can go direct from receiver (where everything is plugged in), over a pair of cat5e cables, to the other where it will end with a male HDMI connector (but still in ceiling, though accessible).  I'm thinking at that point I'll have an 
hdmi keystone wall plate for it to plug into, and I'll plug the other end of that keystone plate into the HDMI -> vga cord I already have which will connect to the projector itself.  I'll tape everything in the ceiling up well to prevent moisture and such from getting in - and this will leave me with a true HDMI plug for a future projector. 
I could also use 
these, but they require power, and are a bit more expensive.  They do, though, have an IR repeater and only require one cat5e cable.
Thoughts?  And thanks again for the help!
ETA: 
Found these.  Look to be everything I'd want!  No power needed, IR repeater for remotes, cat5e -> HDMI and keystone wallplate all in one!  The hdmi extenders over cat5 above were $16 on their own and didn't have IR repeaters, and would still need wallplates and keystones - so all in I'm likely about the same money anyway, and this will be much cleaner.  I'll start with these and report back.