I need to cut a new 32" exterior door in to my masonry block home.
the location of this will be right at the corner junction of two
exterior walls. The type block in this area is the shorter 4"
height...not the typical 8 or 9 inch high hollow core block. I have a
flat roof and this door way will be about 3.5 feet below the roof
line.

Can I cut flush with the perpendicular exterior block wall and mount
my double side framing flush with the perpendicular corner wall...or
should I cut so there is at least some of the return wall stub left in
the corner ?

Also...do I need to support the opening during cutting will some type
of post....or will the block construction be strong enough to cut out
the 32" x 90" or so opening and install the reinforced sides and
header without a temporary support system ?

Thanks, Tim