Oil pulled a Houdini on me..

Hi, I have a 2002 Chevy Malibu 3.1L V6 SFI with 50k. I just purchased about a month ago and the car seems immaculate. A week after I bought the car the check oil light came on. I checked the oil dip stick and it was very low. I took it to Wal-Mart to have it changed, engine oil light gone. Exactly about two weeks later the check oil light came on once again. I added a quart of oil. A week and one day later the check oil light came back on again. Once again I added a quart of oil. My question is does this sound like a problem with the upper and lower intake gaskets and where is all this oil going too?
I drive this car to and from work every day. On the average I put on about 60 miles every day on it. Is it possible that the oil is leaking into the coolant? Keep in mind they are no traces of oil or coolant on the ground and the coolant light has not come on at all. I took off the cap to the coolant reservoir which I was able to do except underneath the cap seems to be another sort of plastic seal or something. I tried taking it off but to no avail. What is that about? I tried using a screw driver to pry it off but no luck, weird.
Another thing is I keep hearing a pining sound (like when you put cheap gas on your car) when I accelerate. This pinging sound only can be heard when the engine has reached its normal operating temperature. When the engine is cold and try to accelerate it won’t make that engine knock sound at all. Could that be the thermostat? Also when I accelerate I hear like a suction type of sound coming from the passenger side of the car coming from the engine. I want to say its coming from the coolant reservoir but I am not positive. Last but not least the cruse control light came on without me pushing the button. I flipped the cruise on and off switch two times but it would not turn off. The third time finally turned off the green Cruise light and has not happen since then.
Anyone has any thoughts in this? I am more than sure I have a gasket problem but would like to get everyones input. Some of my friends have asked me why I bought the car but I really like it because my mother inlaw has a 1999 Malibu LS and never had any problems with it. They have taken it to New Orleans two or three years ago and to Arizona about a year ago. It's basically a family road trip vehicle and has over 170k plus miles. If it is the intake gaskets is it both the lower and upper? and how do you replace them? I've replaced a intake gasket for a 82 olds regency with a cast iron intake, but that is a horse of a different color :)

thanks everyone in advance for everyones input... grat forum!!

Thank you mailbugtp, I stand corrected it's a 3.1L V6 SFI. I corrected my post.

you have the 3.1 i believe

First you want to make sure your cruise control will turn off with a tap of the brakes, if not, that could cause serious injurry. Second the suction noise could be a vaccum leak, if it is that could cause the pinging.

as far as the oil ....? there is no coolant in the oil, no oil in the coolant. nothing on the ground. If you rev the engine in park, do you see blue smoke ?
look under the car also for a leak. Yes it could possibly be the lower intake manifold leaking, especially since you are hearing a pinging. inspect around the lower manifold with a flash light for any liquids.