Don't be in a hurry to spend money. Grafmatics aren't cheap! I suggest learning with three or four conventional holders first. Also too light of a tripod is never a good thing, especially since old Tiltalls go for little and they can handle most 4x5s with ease. Save the bag of rocks for blustery days.
Graphmatics and rock bags solve problems, but they are problems you shouldn't have to be solving when you're just learning. Results are what is going to keep you interested. Stick with simple gear and shoot lots of film---experience = results. You can address any challenges when they come up (and they likely will, but just don't hurry them!--seeing the world upside down and backwards is challenging enough for now, no?)