Noise from underneath

my car, 84 caprice, makes a wretched rattling noise from underneath when i'm driving. (as per the wife, sounds like i'm dragging "just married" can behind the car) especially on less than smooth surfaces. it still rattles a little even on smooth surfaces. it sounds like it's coming from the rear. my first thought is that the old and original exahust is loose and needs to be replaced. does this sound about right?

3 other things. sorry for not putting them in the post. when i start the car in the morning, it usually starts right up after giving 1 good pump of the gas. i'm okay with that. why is it that if i run to the store and i'm back out in less than 10 minutes, the car doesn't start right back up? do carbeurated engines need to always be pumped or will maintenance or replacement of parts cure it?

when i do start it in the morning, i can't even run back in the house right away. i have to wait till the engine starts gunning like it always does and hit the gas to bring it back down. solution?

last but not least, when idling, the car seems to "sputter," "cough," idle weird, etc. solution?

i assume a trip to the mechanic might solve all my problems but it would be too costly right now. as a former employee of a subprime mortagage co, i am currently out of work. are there any small remedies for these problems? are they "serious" problems? should i not drive the car until i can have it looked at and everything fixed? the last thing i want to do is completely ruin anything major. thanks

A visual inspection under the vehicle might reveal what's rattling. The exhaust is always a prime suspect, especially at that age.

As for the startup routine, since the engine is carbureted, the accelerator will need to be operated once when cold to set the choke. That's completely normal. Once started, as the engine warms the idle speed should be higher, since the choke also operates a high idle cam. Idle will remain high until the throttle is opened again to release the high idle cam once the choke has opened. That's just the nature of the beast, and is completely normal.

Misfire or stumble at idle can be a sign of several things, from weak ignition to incorrect fuel mixture. Verify that the spark plugs, wires, distributor cap, rotor, and electrical connections are intact. After that, cleaning the carburetor primaries and checking the mixture control solenoid operation and adjustment are a good idea. Of course, a clean air filter is a necessity.