Hi mate,
Firstly welcome to FOG!
Sorry to hear about the problems you've got, firstly where abouts are you? (if you could add a county or something to your profile that'd be useful).
I'd suggest that the brakes probably just need to have new brake shoes or pads put in, you might need you drums or disks though if it's particularly bad, it'd be worthwhile pulling the wheels off to have a look.
Odds are you can get a new backbox fairly easily and have that installed, if they try to sell you more (unless its needed) tell them to get stuffed, they can weld a backbox on to the exhaust pipe, you don't need a whole new pipe unless it's stuffed.
Knocking in the front could be several things, a bit more info about it could be good, does it happen when driving, or when turning the steering? etc.
Could be brakes, but more likely the suspension in some form, could just be rubbers need replacing or new shockies.
Intermittent wipers is probably just a relay or similar, sounds more like the return system isn't working. It's probably more worthwhile to grab a second hand wiper motor and fit that instead, you should be able to grab one from a breakers fairly easily and for not much £. It's easier than stuffing about trying to fix return systems and stuff.
I'm sure none of it is terminal mate, it can all be fixed.
At the very worst the noises in the back *could* be the diff, but it's probably not likely.
Take a look here you might find something useful. There are some things that you might not have thought of.
It'd be worthwhile getting all the oil levels checked in the diffs and get the grease points greased...
Also change all the oils and filters, it'd probably be well worth while doing that.
Keep us up to date on what happens. And good luck.
Cheers,
Si









