I have been in the process of removing old caulking and putting in new
caulking at the ends of my cedar siding boards as well as in some
slight splits that have formed around nails in some of the boards.
Unfortunately, some of the boards have started to rot a bit due to
water. I would like to replace these next summer before I put a fresh
coat of paint on the house. However, I am wondering how difficult it
is to replace these boards.

I know I can purchase cedar boards from Lowe's, however, I am concerned
with how difficult it may be to remove the boards from their positions
and in turn how to put the new board in.

Is it as simple as removing the nails, sliding the board out, and
sliding the new board in.

Also, if/when I replace, I would like to use screws instead of nails.
Is there a specific type of screw I should use for this application of
cedar boards.