Hasta La Motion!

In the past, if I were to Grade my films for a TV set, I could play it at home and get a "general" Idea what it "Should" look like when distributed to others.

But when your film is being projected on a 10′, 20 ‘ etc. Screen, Via PROJECTION, I have NO IDEA what to expect.
For example,
Will the Blacks be way lighter?
Will the Luma be dark & muddy?, will they be blown out?
Will any grain in the film be 30 inches high?
Should I make a version ESPECIALLY for projections?
If so, what guidelines are there?

If I go to BEST BUY & buy a 100" projection, will that represent a film festival’s Projection (to some degree) ??

Anyone out there with stories about their own film being screened?
Any surprises when you saw it?

Thanks guys,