Help: I want to creat a level switch at a random score

well not a random score, but it would have taken up alot of room to explain it.
what I want to do is have the level go up when the left or right arrow key is hit, between the score 300,000 and 400,000.

alternitivly, is thier to set a timer so that it changes frams after a certain amount of time has gone by.

also, I cna probably find a good thread about it in this forum, but can anybody suggest a good collision totorial. not for lasers, but for something comming at you.

What I am trying to build: a game where you are moving foward constantly but have to dodge things comming at you.
I also want to make it so I cant move the driver off the screen. I tried the totorial on flashkit, but it didnt work at all.

thank you all for your help.
Dan