I think the length is due to their using metric. I believe it is 50 meters.
Puting it up before the sheathing is a bad idea. It is too late by the time it gets to the Tyvek. The idea is to protect ALL the underlying wood from water and to protect against air leaks. If your builder is worried about rips he should not put it up until just prior to putting up the siding. Any rips can be taped with the Tyvek tape.
As far as needing to use the special Tyvek tape? Probably not, but the difference between Tyvek and another brand is probably less than $10 a roll and why take a chance on such an important part of your home. Do it once, do it right.