1. See below
2. Yes:
If your Vim is compiled with +windows (which is always the case if
your Vim is at version 8.0.1118 or newer) just open both files in
split-window mode, either by starting Vim or gvim as (for instance)
vim -o2 filename1 filename2
or (if you already have filename1 open in Vim)
:split filename2
or
:new filename2
then yank in the one and put into the other. The fact that both files
are in the same directory is irrelevant here, as long as you can
access them both (and write the changed one) from a single computer.
(Either filename1 or filename2, or both, can be a full
path-file-name.)
Best regards,
Tony.