Are you doing flight only or as a package?

Can't comment on status benefits but the advantage of flight only as a group is you do not need to confirm passengers until nearer departure. However, was more expensive than booking individually.

There is a group check in at T5 and suspect you would all have to use this so no OLCI. Seats will be pre-allocated with no choice.

I took a group of 20 to NY but found it cheaper to book as a BA holiday. Still some flexibility to remove somebody if need be. As such I also earned avios and TPs. Remember if doing it this way to put yourself on the most expensive booking to get the extra avios for a BA holiday.

Golds can use TCP and can email asking for all specific seats to be assigned across bookings without charge.