As to your question about how long it takes, it varies based on the repair. If your friend's MBP took 5 days to have a logic board replaced, yours could take 2 weeks and this would be normal. It all depends on if the part is in stock, and if it's not, there's no telling how long it could take.
Someone said something to the effect of Apple Stores being faster. Since Apple Stores and non-apple service shops order parts from the same place, it will make no difference. Still, in my experience, repairs tend to be faster at small, privately owned non-apple service shops rather than the official Apple Stores.