These are basic projectile problems, and I will provide a YouTube video that will basically give you an answer to the first question.
I would convert these values to meters:
10000 F would be 3048 meters and 500 FPS would be 152.4 M/S.
You should know that there is an acceleration in the downward direction, as there is gravity (9.8 M/S). There is 0 M/S initial velocity in the vertical direction.
d=V1T + (1/2)at^2
-3048m= (1/2)(-9.8M/S)t^2
-3048m= -4.9t^2
622.0408= t^2
24.9 m/s = t
d= vt
d= 152.4 x 24.9
d=3800.9626 m
(note that I punched all the figures into the calculate at once, so it might be slight off if you calculate from those figures)
In the second problem it seems like the 5ft information is irrelevant, as both sides are above the same level.
For your last problem:
http://www.youtube.com/watch?v=tUUU8ZnlqMU