Woodworking is an endeavor that essentially a scalable version of how to skin a cat. You can accomplish a lot with a hand saw, some chisels, and some planes. You can also accomplish a lot with a circular saw and router. It's really how you want to accomplish the same tasks. As you already have a circ saw and miter saw you're already ahead of the game (build a straight edge jig or buy one for the circ saw) I don't have a Jasper brand jig, but I make due with the Milescraft circle jig for my router and it's fine. I have a Bosch 2.25 HP router with a fixed and plunge base. I haven't thrown anything at it that it couldn't handle (just take multiple small passes). It's big enough to take care of most jobs, but not too big that it's unwieldly for trim work. That said, most routers in that horsepower range will work. Routers are pretty simple tools and even cheap ones still spin straight and true.

You can never have enough clamps. New clamps are expensive. Look for sales, shop at harbor freight, or better yet look at CL, Facebook, yardsales, or auction estate sales. If you do buy new, buy pipe clamps and black threaded pipe. They're way cheaper than parallel clamps. also look for a couple of decent squeeze clamps. They're super convenient, however the cheap ones don't have enough clamping force.

In terms of router bits, I have these and they have served me well. You'll need more eventually, but buy them piecemeal for the specific jobs you need them for and look for carbide bits. Freuds are nice, but a little pricy (although not close to the most expensive).

Eventually you'll want a table saw, but that's once you're really committed.

Finally, dust collection and a good mask are really important especially with MDF.