...they are but your questions regarding freewheels and indexing compatibility only apply to geared hubs and track bikes don't use these.
Re the bearings issue, you're right in that PW's have a reputation for producing excellent bearings. But as Caferacer points out you risk jumping through a number of hoops concerning availability / redundancy / cost in order to get this. I'd also question whether the difference in terms of reliability, longevity and drag reduction between a set of PW bearings and another 'lesser' brand like Shimano or Campag would be a factor in practice. The higher end Ultegra and Chorus models from the latter are well sealed, fairly cheap and spare parts are readily available if you need them and any extra losses in terms of bearing smoothness will be undetectable, particularly for commuting / touring.
If you're not tied to the 7 speed freewheel route I'd second the suggestion to invest in more modern equipment.