I'm hoping someone may be able to help as yet again i'm finding that things aren't straightforward!
I'm trying to book a LONE5 departing in November. One of my legs is HANOI to MEXICO CITY and using the booking tool, the only option is to go either:

HAN - NRT - DFW - MEX or HAN - KIX - NRT - MEX

I rang BA and asked why i could not simply go HAN - NRT - MEX as individually, these flights are available and they said it probably had to do with the fact it was a codeshare flight. The lady suggested that instead i book the flight as 2 flights rather than connecting flights. So i have HAN - NRT arriving 06.45am on 14/02 and then NRT - MEX at 17.20 on 14/02, This frees up an extra segmnet that i needed.

However, my question is: would i still be considered to be in transit? Would i have to go through departures and then check in for the next flight seperately? And also, what would happen if the first flight was delayed, would i still be covered as i would if i was in transit?
Hope that makes sense!

Another part of the trip is a return flight from SANTIAGO to EASTER ISLAND with LAN. These will have to put booked with dummy dates, but i just wanted to check that this flight is still likely to be available in September 2010 i.e that it is not seasonal?

Thanks for your help