So, and I would appreciate some other players who have been playing before 1.05 to chime in as well, a few practical things I've learned about supply from my first few games (spoiler... it is headquarters are everything).
1. Headquarters placement is key. Deploy your headquarters were they are needed to support units, but also along roads or, ideally, in towns or cities within a couple of hexes of the front. They will build more supply there then in non-road or city hexes. Keep your headquarters moving to support your main thrusts.
2. Ports are important to draw supply, but only to a point. If the enemy has a headquarters ashore, even if you reduce all the ports to 0, their units will still be able to draw supply. With headquarters it is very difficult to starve an invasion of supplies.
3. Headquarters can act as mulberry ports for limited periods of time, allowing non-marine units to draw supply from them even without a port. Would appreciate it if somebody would chime in with how long that effect lasts, and if any technology change or increase the effect.
4. Weather affects supply. Rasputitsa and snow will reduce supply available to all units. So those units that were happily at 5 supply one year in Russia may be at 3 supply the next turn as the muddy season sets in.
Anyways, this is some discovery learning that I had during my first 4 multiplayer games. If anybody else wants to come in with additional handy hints it would be much appreciated.