Does anyone have any information or stories they can share about velamentous cord insertion and/or vasa praevia (low lying placenta)?

I had my 20 week scan two weeks ago and was told by the sonographer that the umbilical cord was attached to the membrane of the placenta rather than squarely in the placenta - in med jargon, a velamentous cord insertion. The OB on duty and the sonographer both assured me that there was no risk to the baby, but that there may be an impact on the labour in terms of bleeding, yada yada yada...essentially told me not to worry too much. So I didn't.

Two weeks later had a follow-up appointment with the doc at the Mercy Family Birth Centre and asked about the cord insertion and what that meant.

Doc told me - very cavalierly I might add - that I had a low lying placenta ('placenta praevia or 'vasa praevia) that was blocking the entrance to my cervix. He told me they would know more by a 32 week scan, but that if the placenta didn't move I would have to be transferred out of the family birth centre and into the main maternity ward for a c-sec.

** note subject for another post - I thought it was obvious that I was in the birth centre because I have strong beliefs about natural birthing etc, so I was a little irritated that the doc was so casual in his mention of the c-sec **

Anyway, did a bit of online research regarding velamentous cord insertion and vasa praevia and was very disheartened and somewhat alarmed to learn that the combination of these two factors puts the baby at a high risk around the time of the due date.

Does anyone know the likelihood of the placenta moving up higher?
Is it worth having a scan earlier than 32 weeks to see if the placenta has moved?
Does anyone have reliable info/stats on these two conditions?

I plan to contact the birth centre for more information, but am also hoping that someone within this trusted network can point me in the right direction (or at least alleviate my fears).

Thanks in advance!