since you can not drop land in express (you can drop it but only after 20% of the set has passed) the options are high bpt or just running with empty land

so i think your bpt is ok
i would rec getting your mil strat up
you can be very effective saturay afternoon

if you use your building bonus of-40% to build 100 buildings a time for ten turns you can use one bonus to save $8.8M which may be the highest use of any bonus