well i´ve tried many different unit´s being a ford/mazda specialist, the only one i´ve had luck with all around is from www.clutchmasters.com they have direct apps. in 5 different stages from step above stock to full out race. my LTS has a stage 2 and has been wonderful, nice bite with long life. installed in 99 and has barely any wear, even with 25000 miles since then.
Putting a new clutch in is a pain in the a**. I put one in my 87 EGT. You have to remove both front axles and the transmission itself (and of course everything that is in the way of the axles and transmission.) If you have the right tools its do-able, but time consuming. It would be easier just to let a garage do it. As for a test to see if your clutch is bad, i really don´t know. Usually if it is bad you can just tell.