Source Tactical 3L but don't fill it all the way unless water will be unavailable due to the weight, Sawyer squeeze, smart water bottle and 1 Nalgene. Trying to cover all bases without adding too much weight.
Plug the 64 into your laptop, open onx on the laptop and under my content, select import. Navigate to the Garmin/gpx folder and import the waypoints and tracks.
Also you can use the Garmin Earthmate app.
I have been using Brownings Hells Canyon Gore Tex jacket and pants and have not had problems with wetting out. Their material is a little heavier but wears well.