New
#780
Hi Mike.
The USB stick can be very small, 1GB, or smaller. Very hard to find. Basically Windows RE and Macrium. This can be fit on a CD after all so less than 500MB
I would be installing MR on C: as it just makes it easier to invoke and run a backup. Also easier to update.
If it becomes a hassle to run most people eventually avoid or won't keep current.
You do not have to add to boot menu, some of do and we keep an Image on board for a quick restore. Definitely you should keep several versions on external and disconnected.
I use two USB's and I alternate when I make new rescue media. It is not necessary to update Rescue Media with every release, thankfully as there were three updates in May. In the release notes they will recommend if new boot media is required. I do it ever two or three updates. (and I never update when a new update is first released, I wait a week.)