"First problem is that when I start the car, it starts shaking and
jolting and then the RPM's go up to about 2500 and then........"

Remember, a Malibu is a running animal. Your Malibu is just raring to
go. Put it in gear and just take right off. Your mileage will be better.

Well Ash:

To be perfectly honest, with perhaps the exception of the spark plugs the
rest is better left to qualified personnel and not a beginner, such as
yourself.
The newer vehicles such as this one has so many sensors which send
information to a central computer, that it would be impossible to diagnose
the problem from your description. Dealers, garages and some of us have
these code readers that plug in under the car's dash and run a diagnostic
check on the vehicles systems. When done, a series of numbered "trouble
codes" come up, that point to specific areas of the engine and suggest
possible problem areas, so this is the best place to start, in my
opinion.
Shop or service manuals are typically aimed at specific vehicles, so
although you can  get ideas from another manufacturer's manual it is
strongly suggested that you get one for your car...IF...you are planning
to do more work on your own car.
The remaining three spark plugs (cylinders 1,3&5) are located at the back
of the engine, just out of view and a little tucked away. Your boyfriend
should be helping you through this process. What kind of guy let's his
woman do her plugs alone for the first time? A healthy plug is usually a
brownish/tan/grayish colour.
Second...gas guage can be a tricky item to fix and is rarely something for
the amateur mechanic. Likely it is the sender unit located inside the gas
tank (at fault) that transmits info to the dash and your fuel guage. To
service this, the tank should be completely empty and usually although not
always the sender unit has to be replaced with a new one, Sometimes a
broken or rusty wire connection at the tank can be the culprit etc. After
tinkering with cars on and off for 20 years I might do this job but
certainly wouldn't advise you to do it without the assistance of an
experienced mechanic...there are too many small problems that can pop up.
The sender units are usually fairly pricey also, so beware. Get several
prices before you consider buying one and don't buy untill you're certain
it needs to be replaced.
Third....it just keeps getting worse, eh? An accident car is never good
news. This sounds like it is either a cv joint or a wheel bearing with a
slim chance it could be the brakes but I somehow doubt that. Best option
here is to have it taken to one of you local muffler or front end
allignment shops and opt for the FREE estimate process. Have your
boyfriend book the appointments..at least three and take the car in. With
estimates and service pricing, women are still unfortunately taken
advantage of, in the automotive industry, unless they are very informed
and deal with mechanics and service advisors regularly. Have each place
describe the required work and list the required parts that THEY SAY need
be replaced. DO NOT allow anyone to do repairs until after you have 3 to 4
detailed estimates in front of you and you have carefully reviewed and
compared all of them. Cheapest is not always the best way to go and I
prefer to have these types of repairs done during the week when typically
the more experienced employees tend to be around the shop. Sometimes on
weekends, shops are manned with students who can still be very good
workers but may not have as strong trouble shooting techniques.
Fourth...Yikes, what a list. The fuel filter (get a shop manual)is located
just outside the gas tank, actually in front of it, although this picture
does not label it as the filter. It is an awkward spot to get to. Never
get under any car without good car stands being put in place first.
Well Ash....so the story ends.
Good luck with your mission.