Wheel bearings will contribute a grinding noise and reduce your gas mileage. You can check them by jacking the wheels up one at a time and pulling/pushing at 12 oclock and 6 oclock, any looseness will be either the unit bearing or the balljoints. Do the same thing at 3 and 9 oclock and looseness will be unit bearing or steering (you can then look at the steering joints while doing this and figure out if it's the unit bearing.) Also they'll feel rough when you turn them if they are getting bad.
Balljoints will also contribute to looseness at 12 and 6 oclock.
Steering is easiest to check with a helper - throw it in park, start it up, have them turn the wheel back and forth while you look at the TREs, etc. You should also be able to see any blown bushings in the control arms and track bar this way.
You can replace the bushings in the control arms, doing the uppers is worse than the lowers. Remove ONE ARM AT A TIME (you may want to buy new nuts and bolts in advance if there is much rust or you think you'll break them), remove bushing, press in new bushing, reinstall. The XJ LCAs are C-channel pressed sheetmetal and can be troublesome to press new bushings into, I've always just swapped in new control arms with new bushings prestuffed. The UCAs are the same at one end, at the other end the bushings are pressed into the axle - everyone has their own favorite method for these. There is an article floating around about using pipe fittings and hardware from Home Depot to make a puller for them but the easiest method I have heard yet is to grab an electric drill and large (3/8" to 1/2" or so) drill bit, drill into the rubber of the old bushing. The drill will want to walk around the center sleeve, let it, it'll tear most of the rubber out for you. Rip any remaining rubber out then use a sawzall, hacksaw, or hand file to cut through the outer bushing sleeve in one spot, then it'll collapse nicely and you can "peel" it out with a pair of pliers. I am pretty sure I heard this method from MrSimon. Other methods are to burn the bushing out (smells terrible, leaves residue everywhere) and to press it out which requires more money and isn't quite as satisfying.
EDIT: be careful pressing the new bushing into the passenger side UCA mount on the axle. It's easy to compress the mount instead of pressing in the bushing by accident if you don't brace it with something.