If all the bushes are OK then you can change the ball joints but i do remember reading on here that the rivets are a pig to get out.
Depending on price difference it might be worth changing the complete things and have done with it.
have a search for the thread, if i remember they ground the heads off the rivets but still struggled to knock out the rivets for some reason. changing the whole lot is probably easier
Breaking the taper on the ball joint is the only bit that might be awkward.
Have you actually found play in the joint? if not check the back inner bushes, you can remove the end nut to get a better look.
Not physically checked for play yet but looking at the joint and comparing it to a pic you posted on another thread, they seem to be well collapsed - and the clunking im getting seems to point to that ball joint - I hope !!!
No it's not necessary to remove hub assy. It's the same in Rave, I think they show it that way to give better access to break the taper on the ball joint with the factory tool.
I changed one wishbone without removal of calipers etc. The ball joint had failed and it was easier to change the whole thing. Take the under tray off, even though it doesn't look like it needs to come off as you can't get the joint bolt out.
To release the ball joint, use an open ended spanner and undo the nut until it is free of the nyloc (VERY IMPORTANT). Now you need a ball joint spliter to separate. As I was discarding the arm, I used a big hammer. Now that the joint has separated you can remove the nut completely and complete the separation.