It is true that you can cut many doors to fit your current opening, but
I would consider enlarging your openings. This is very simple because
they are interior doors so you won't have to mess with siding and
brick. Also, because you are making your openings larger and not
smaller, you won't have to mess with adding and finishing drywall.
Also, your trim pieces will be much easier to find already pre-cut to
fit. Your re-sale value will alsom improve because a savvy homebuyer is
going to be a little deterred by having small door openings