The film start issue is a dirt and old grease thing.... and you know what that means.

The softness could be that the viewing and taking lens are out of alignment. Check over images to see if there are areas in sharp focus other than what you thought you were focusing on? Lens alignment could be off- not unusual for any TLR. There could be old oil and such hazing the lens.... you know the answer to these issues!

As to the Hasselblad question, there isn't a simple answer. I think the 120 is a pretty darn sharp lens in its own right by reputation? Tessars aren't known for 'bite' like more modern lenses, but they are very capable and shouldn't be grossly soft compared to other lenses. Personally I don't like the blackout after firing the shutter on a Hasselblad and find a TLR much more enjoyable to use in the street and such. I might think about this first- which camera type works well for you, fits the way you like to shoot?