I have a specialized stumpjumper fsr expert and i am wondering if anyone can explain the front and rear shock adjustment? Which way to stiffen and what settings people like to start with? Also how often should i check the rear suspension air pressure?

You might take a look at the suspension setup videos on the Specialized site. Those plus a quick read of the owner's manuals should get you pointed in the right direction...

i didnt get an owners manual when i got the bike but i'll definetly check the site thanks