Well I finished several more games on the universe starter set map. On the avenger's side, there is a staircase. Can one attack from the square with the blue square to the square with the green square and vice versa or does the black line block it?
http://img95.imageshack.us/img95/9189/map4vu.png

If there are only 2 squares of stairs (meaning the green square is the top square), then you can make a ranged attack to the blue square, but not a close combat attack (unless you have Leap/Climb). The top square of a staircase is considered elevated.

Sorry I didn't make the picture clearer. The square with the green dot represents the bottom of the stair case and the two squares underneath it are level with the square with the green dot.

On another note, how come soaring characters can't range attack ground characters when ground characters can range attack soaring characters and when elevated characters can range attack ground?

Game balance. If soaring characters could shoot down to grounded or elevated levels, you might end up with my V Wasp versus your V Quicksilver and I could just move up to soaring and keep trying to shoot you and there would be nothing you could do about it. With the way the rules are now, at least I'd have to come down to a level where Quicksilver has (theoretically) a fighting chance to hit Wasp.

Unless the other guy is playing a figure that has HSS or is a Transporter in which case Quicksilver is screwed.

I understand the game balance aspect of it. Could someone answer the line of sight question for me?