major oil leak

i have a major oil leak, and i know nothing about cars....first, yes i checked the oil, the oil pan and it's nice and tight...the plug is there and tight. when i drive, the oil pressure light comes on and off erratically...it started doing it about 2 days ago, just when i was coming to stop or going. now, there oil all over everything.it ticks like crazy and there's a lot less power. there's at least half a litre of oil for it sitting for 5 minutes warming up. i have the stupid, rare...crappy 2.3 quad four 95 engine...so first question, can i even get an oil pump for this engine, will 2.2 or 2.4 fit? or could it be some gasket. it look's like it's leaking where the aluminum head meets the block (right lingo i hope).about an inch from the top on the right side (drivers). there's a metal fitting with a rubber hose...what's this hose for? my brother said something about some gasket or o-ring being nortorius in the cavalier for leaking...any idea's would help me greatly...before i go out and dump another grand into this thing
thanks, can i just say you guys have been life savers for me and have saved me tons of money!!!
your all great!

Head gasket, is a leaker. I would say have it checked out. and get a multi layer steel head gasket. then after the head gasket change, don't get on your car hard for about 1000 miles... that is if it is the head gasket...

(Also could be a cam-sencor, mine have been warped causing oil leakage. also check the oil filter. make sure that is nice and snug.)