Just got back to this thread. You're really on top of this.
If you don't have a jointer, it can be hard to find wood that is really straight. It is possible to use a table saw to cut a straight edge, but it will require making a carrier that runs in a miter slot and holds your not-straight piece solidly. The carrier type of jig requires you have one really straight edge, and the best way to get that is to use a factory edge on plywood to start with. You cut a long strip off the end and that will produce a straight edge on the cut off piece as well as give you a new straight edge on the leftover. You will need this for your fence as well.
You can also use a large hand plane to flatten the edges and thickness of a board, but for the wood you buy at local stores, the table or circular saw method will work for far less money.
That straight edge will form part of your triangle braces for the fence, plus a straight edge for the flat part of the fence as well. Table saws are by far the best way to cut these items, but it has to be set up correctly so that the blade is aligned with the miter slot, and the fence aligned with the slot and blade, but tilted very slightly away from the blade (about 4/1000 will do.
You will also need a straight edge to guide your router as you cut the grooves to hold the T-track, if you choose to use them. Once you have your fence set up, it's pretty easy to cut grooves.
I noticed awhile back that you wondered about mounting T-track on the face of the fence. Yes, it's a good idea because you can mount a feather board vertically to hold your workpiece down. Pix of multiple featherboards in use.
Personally, I think it's best to have not only the solid fixed fence, but to put T-track on it to mount a second split fence in front of that. Tbolts link the two, and you can shim them to make both sides align perfectly across the front surface. Use card stock for shims. That way you have proper support all the way across without having a slight notch as you cross the center of an uneven fence.
An incentive for doing the fence just right is that you can now use the router to flatten one edge of uneven stock on the router. You add a long shim(s) to push the left half front fence out about 1/16 (1-2mm) and line the straight bit up with the forward fence. When you run a piece through it, it will gradually shave off the crooked part. This is what a jointer does, but it also can flatten a wider piece. Jointers are not cheap. Start with pressure against the right fence, then as the piece moves over the left fence, shift the pressure to the left. This works for mildly curved stock, but not for badly crooked or twisted stock.
Last word on speed squares. They are seldom really square. When you buy one, pop for aluminum and take your draftsman's triangle with you. You will use the draftsman's square a lot to check for 90 degree angles, and occasionally for 45 degrees. Hopefully your fence will be 90 to the table, but if your draftsman's triangle says no, consider building up one side of the bottom with tape until it is.
If you don't have a table saw, you can use an edge guide to make that cut. See pix.
Making right angle triangles to support the fence a perfect 90 degree cut is more challenging without a table saw, but you can use a circular saw with a speed square. Hook the wide edge of the speed square on one straight edge and run the saw against it. Cut extras and check for the exact 90 angle with a good draftsman's triangle. Keep and use the good ones and reject the ones that are not as close to perfect as you can measure. If you can make the triangle supports out of solid wood, not ply, they will be easier to install with screws and/or glue. Pre drill holes for screws!
When cutting with a circular saw, the face of your piece should be down to reduce chip out. Another trick is to put painter's tape on your cut line, preferably on both sides. Rub it down firmly. Doesn't prevent all chipout, but greatly improves it.
Rather than spend a lot of money on the Rockler router fence dust port, you might just want to add a box behind the opening area of the fence with a simple dust port on top. Sometimes you can find pvc fittings that will work with your dust collection hose. That way you can use local parts.
For sawdust collection, given your situation, consider a combination of the biggest shop vac you can get (2.5inch hose), and a Dust Devil cyclone with bucket. Will work for you for a long time, given what you're doing. Won't break the bank and will do a good job.
Wow, this post went all over the place. Be well down there.
The more I do, the less I accomplish.