1) TZRs are alright, though the Aprillia RS50s tend to be a bit quicker stock on top end.
2) its autolube, you fill up a seperate tank with two stroke oil and it feeds the oil in automatically
3) My DT has done near 28,000 miles and still on its original seals, bearings e.t.c (although the gear change seal is starting to weep), i have only changed to a big bore, RS50s tend to be around 20,000 so i would imagine the TZR would be similar depending how you ride it, if you thrash the bollocks off it then it may need new seals and bearings sooner than it would if you cruised