Re: Starter issues??
OK, may not be battery, but a dud battery would still present the same symptoms. As I said 10.8 to 12.4V isn't enough to start the car. If the battery is a dud, it will make a clicking sound as you try to start it - there's enough juice to energise the solenoid but not crank the engine. A dud battery will also power the fuel pump and other stuff because that is all relatively low current.
Another possibility is the alternator (I think it's called a generator in the colonies!). If it's failed then the battery isn't being recharged as it should be.
I don't think its the starter motor though because it's still working allbeit intermitently. It may be a weak / loose electrical connection, relay or earth (ground).
10.8V to 12.4V is NOT enough to turn an engine over, the parts store guy only said it 'should be OK' - not it is OK. Although car electrical systems are rated at 12V, the battery generally puts out 13.8-14.5V How old is the existing battery? They can have a cell fail, If you can change the battery I'd do that first because it's an easy an relatively cheap fix......