Apologies if this has been covered before: a quick search didn't turn up definitive answers to these questions.

In the near future we will be travelling in First with two 10 month old infants from BOS via LHR to JNB. I am concerned about our seating arrangements, and want to ensure that we are assigned seats that will work best with two infants.

Currently our BOS-LHR flight has us assigned to seats 2E and 2F; the cabin configuration for this 777 aircraft is is 1AEFK, 2AEFK, 3AK, 4AEFK, 5AEF.
Our LHR-JNB flight has us in seats 4E and 4F; the cabin configuration for this 744 is 1AK, 2AK, 3AK, 4AEFK, 5AEFK.

Could anyone with experience let me know whether our current seats will work well with infants? My impression has been that 1A and 1K are preferred when travelling with infants. We would like to use BA's Britax infant seats: is this even possible elsewhere in the cabin?

Also, how many oxygen masks are provided for the middle seat sections in First? Thus far we have travelled only within North America with the babies, and have found that on other airlines the number of masks per n-seat section = n+1, so two infants cannot both be seated in a fully-occupied (by adults) seat section. Does anyone know whether every First seat has an extra oxygen mask?

For those who fly out of BOS with infants - are the Britax seats always readily available? I did call BA to ask about our seat assignments and to see if we could pre-arrange the Britax seats, but the person I spoke with assured me that "the last row middle seats" in First were the right seats for travelling with two infants, and that the Britax seats were "like wheelchairs: there are always plenty available". I'm not sure that either statement was entirely accurate.

And finally, for those who have had to gate check strollers en route to either LHR or JNB, have you been promptly reunited with your stroller upon deplaning, or do gate-checked strollers end up miles away at the baggage claim?

Thank you for your advice.

baobab