before i buy

hi again
just before i buy my projector there is two things i would like to know
the projector i have decided on is the themescene H30A
this has some good reviews and sounds like it will do the job
but
keystone correction,
will it correct an image if the projector is mounted to the side of the screen
or will it only correct from the higher or lower position ???

also the screen size
if the throw distance is 3.6m and a screen size of 1.85 x 1.39m
is this further ajustable to fit the screen exactly or is it just a case of moving the projector to create the exact image size.

thanks for all the advice it has all been very helpful