Hi mumbot,
I had a placenta praevia with my first child nearly 2 yrs ago, which was missed at the 20 week scan, and only picked up by a bleed at 39 weeks.
Once the hospital had established that it was pp which caused the bleed, there was no option but to have an elective section, as the placenta was covering the neck of the womb completely (it was the most serious placenta praevia there is).
The section took about 45 mins in total, the team were very relaxed, and bubs arrived safely. I have no idea if this was longer than a section where the placenta's in a normal position, but no-one appeared worried, and I don't recall them telling me they had concerns.
As for bleeding, I had post natal bleeding for 4-6 weeks, which I think is totally normal!
If you have worries, then I'd say speak to your consultant, but in my experience, I had a lovely delivery, even if it wasn't the homebirth with flowers and candles I had hoped for, and the most important thing was that me and bubs were both safe and well.
Good luck!