Geddon

Have a 4 dr MY00. Have had it 6 mths now. I believe it has the standard speakers in it but has a Sony head unit in it and an amp in the boot which is only wired in to the rear speakers.
I am well into home Hifi and want to spend a bit of money on sorting the car. I don't want wideboy bass but I do want to get rid of the speakers rattling and distorting. Also need to get the amp wired to the fronts and stop the CDs jumping (CD changer I guess).
Problem is I have no idea what speakers to get or anything I am also a bit scared of going to the wideboy ICE shops.
Any advice on what to do and get to sort my problems?
Also how much am I looking at?

Thx in advance
Pete