My roof is comprised of composition shingles, 3 tab I believe is the term -
not sure of the lifespan (might be 15 or 20 years).
Looks like there are two layers on the roof now but the shingles are in such
poor shape (old mostly) that I believe this spring is the time to invest in
a new roof.

The roof has always had ice dam problems in the winter mostly because my
attic is not ventilated very much at all. Living in NY the gutters in
winter (every winter) typically fill up with melting snow and become a
massive block of ice. There are several minor leaks in my attic
(un-finished).
The wood roof underneath the shingles is what almost looks like
tongue-in-groove style. Some of the wood planks has rotted away and the
only thing between the inside attic and outside sky is the roof shingle
themselves!

My upstairs is cold in winter (if I touch the inside ceiling it is rather
cold), and warm in summer (if I touch the inside ceiling it is rather warm).
I have central air upstairs but it always labors/starins each summer. I
have a feeling that when the upstairs was added as an addition the builder
either skimped on insulation or the amount was/is inadequate.

What I want to do is have the roof shingles replaced and possibly the
underlying wood (perhaps have them tear it up and lay down plywood). I also
want to see if they can lay (or blow) in additional insulation material when
the roof is open. I also want them to put in a rubber membrane at the
gutter line (up to about 18 or 24 inches) to help prevent ice dams and water
backup.

Ok, now - any ideas or suggestions on what I want to do and if it is a good
idea?

Thanks.
Walter