Corners tend to be wasteful. You may find the SW corner of your garage more useful if it were to contain a single bench 7' long as opposed to the L shaped version illustrated above. You end up with less counterspace - 14 square feet vs. 18 square feet, but you end up with more
usable counterspace. You would also have full and easy access to everything under the bench (if you are considering building a bench there). Another option would be to build just the 5' section and store the tool chest on the 46" wall and slide it in/out as needed for access. This would not be ideal, but it would make efficient use of the available space. In this latter scenario, I would build the bench so that the toolbox could roll under it. That way you would have additional stationary counterspace.
The Delta shelf track/brackets you linked are rated for basically 240 lbs per linear foot. At that rate you could store an engine block on them if you were so inclined. I would consider the limited configurability outweighs the weight capacity unless you have a use for that kind of weight capacity and be inclined toward something more like
this. 90 lbs per linear foot and you get significantly increased flexibility. They are only 20" deep, but you can make the plywood shelf you put on them as deep as you want. If you prefer the Delta, those brackets could be extended out another 8" with a simple bracket made out of plywood or just replace the entire bracket with a piece of appropriately sized rectangular steel tube. Drill a hole and you're done. The Everbuilt (or similar) option I linked above seems like a faster and more convenient path to completion.
If you go with the 2x4 construction and run the verticals all the way to the ground you only need to anchor them to the studs in a few places to help hold things in place. The 2x4s are providing all of the structural support. Anchoring them to the wall only serves to resist lateral movement and prevent tipping.
What are you planning to store on top of that wide open span over the center of your workbench? A 2x4 can easily span that 9' with no other support, but I wouldn't load it up with paint cans and lead shot. If it needs to support a sizeable load, I would add some additional shelf brackets to help carry the load or significantly increase the depth of the beam. Run a 2x10 on the front and a ledger anchored to the studs on the wall side and you could store engine blocks up there, too.
Formica is a thin laminate - 1/16" or so - intended to be applied over a supporting surface. To span the roughly 4' open space in your workbench, you would definitely want a 2x4 on edge if using a plywood top. For a 24" deep work surface, you would want a second parallel one centered between the wall and the front - or - a couple running perpendicular between the wall and front like in your typical home floor/deck construction. For a
very solid work surface, laminate a bunch of them together like this picture provided courtesy of the web.