SYD-SCL is operated by LA using 343 equipment and has a single row in F, so not much choice of seats there (LA has nice food and wine, but a crummy F cabin). All F cabins have at least one basinette position (must be required by regulations, as all airlines have it), it seems to be either the first or last row (usually first). You can get seating plans at the web sites of the various airlines that you are flying.
If you are trying to maximize the experience of flying in F your flight selection consists of some of the worst for F on the Oneworld network (in terms of comfort, quality of service). For example AA flights out of GIG are infamous for being sub-standard and having surly crews (some have even reported F meals being unavailable, and later seen to be eaten by the crew) ... very atypical of AA. JFK-LHR is very short flight (7 hours), which makes it much less comfortable than the longer west coast (SFO/LAX/SEA-LHR) flights. LHR-SYD is better done with a stopover in BKK or SIN (or even better to go LHR-HKG and then HKG-SYD on CX). While BA is superb LHR-SYD, the flight is just too long for pleasure, even in F. In terms of enjoyment of inflight and ground service, you would have done better to fly SYD-AKL-HKG-SFO-JFK-YVR-LHR-BKK-SYD or something like that (within the 35K mile limit for QF Oneworld awards). If you were constrained to go to SCL, GIG and JFK then your routing is mileage limited and you had little choice in airlines; but since you are worrying about getting the best seat, you should be aware that you could have had much better planes and much better airlines by using a different Oneworld routing (makes the seat selection rather insignificant by comparison). Be sure to make use of the Concorde Room at LHR, the nicest perk of your F award given your routing.