Great list!

Here are my humble suggestions:

Fire starting:
replace the matches with a mini Bic
Consider a large ferro rod. (MagFire Pro?)

Shelter:
Consider a Coghlan's Emergency Bag as a shelter. Makes a great wind and rain proof bivy bag. Two trash bags you can fill with leaves or whatever could be used as a blanket to keep you from freezing.

Signaling:
For the zillionth time; the StarFlash sucks compared to a glass mirror.

Water:
A Ziploc bag may provide more utility.

Medical:
OK, could be better.

There a lot more things you can carry that are useful but it is always a balance of how big a pile of stuff is it before you stop carrying it " all the time." Less that you have, is better than more, sitting in the car or at home.