Yeah I think each manufacturers isofix base will be for their brand of seat only, and maybe only certain seats even then. We had the easy fix base with the cabriofix last time - it meant we didn't need to be tied down to getting another maxi cosi when we went up a stage, whereas with the family fix, we'd have felt obligated because of the higher price. Something else to think about 
Yes, jen, our poly was picked up at the 20 week scan. I was then measured quite closely by my mw and had an extra scan at 34 weeks to check that and position of my placenta as it'd previously been low lying. I was worried about it - probably spent too much time consulting dr google - but I was pleased it had been discovered and monitored, even though everything was fine in the end.
Baby doing humungous kicks right down near my bits at the mo. It is his/her party time at this time of day but it does still take me by surprise!