My friends pro 2 didnt spin brilliantly at first but now it spins great. I think the hub looks and sound fine. Bit off topic but were did you get that tyre from.
Theirs a good chance it will fit if you grind the freewheel tool fittings off but 118 and 113 lengths tend to be around the same price so you should try to get a 118. 127.5 bb's range from £50 upwards
get one of them strong half link chains. Im not entirely sure what there called but my friend had one and there mint. Im sure someone could give you more information on these chains.
Heres my first ever video. Before this I had never used any editing program http://tv.isg.si/site/?q=filebrowser/medwaytrials click on chris vid.wmv (it is the only one there)
Heres my friend wills fully built aorta 20". http://www.pinkbike.com/photo/779258/ Its pretty good for everything, nice on the back wheel and very flicky.