i have a year studying at university in japan starting in september 2003 and really want to do a rtw trip as follows :

lhr - bkk (ba)
bkk - sin (cx)
sin - hkg (cx or qf)
hkg - nrt (cx)

all at the begining of september, and then in june/july :

nrt - hnl (aa operated by jl)
hnl - sfo (aa)
sfo - jfk (aa)
jfk - lhr (aa)

i want to purchase a business class ticket and i have the following questions (sorry if there are too many/they have been answered before) :

1. is the above itinery ok?

2. what suggestions would you make/what other options are open to me?

3. what happens if there is no availability in business - will i ever get downgraded to coach?

4. where there is no business class (eg domestic usa) will i travel in first or coach?

thanks for your help...dx