#1: I don't know about disconnecting it but to replace the bushings just undo the 4 bolts holding the bushing mountings and pull them off. The rack will come loose in your hands. It's not free (I don't think) but you can work the new bushings onto it and put it back
2: use more wd40 and try pliers if you can. Might be possible to get at them from the other side too, i.e. where the tip is. No real good way, changes depending on situation. searhc google
3: if jaw puller isn't working you're not doing it right. Also jaw puller still isn't EASY but it's the best way I've ever found. Use washers too they help. What is not working? it wasn't THAT hard when I did it.
4: look in manual for suggestions? or check
MKI MR2 Write-Up Page and see if thers' info there
same site has info about ball joints i believe
All I did was bushings. Jaw puller did it for me. Lot of wrench turning and washer destroying but all it really took was time. Wasn't actually difficult. Most difficult part was putting suspension back together and getting the polyurethane grease off my fingers and tools.