1) Yes (well kind of - it's not 'just' Golds...Silver or OW equivalents too and some other exceptions, none of which sound like they apply to you though). See www.ba.com/seating

2) You want to both be on the same PNR to stand a chance of being seated together. Award tickets are fully flexible until the first leg is flown. So if you want maximum flexibility the way to go would be to book two separate bookings - the first for you both ORD-LHR, the second for you both LHR-ORD