MDF can "technically" be a better material for cabinets but I do not suggest using this material unless you are working outdoors or have access to very good dust (and fume) collecting equipment. I hated it. Good quality plywood is much more enjoyable to work with and healthier.
Table saws are great but you can do a lot with a cheap circular saw and a clamp-on guide, or even just a straight board and clamps.
A router is great for cutting circles and I've even used mine (with a guide board) to trim or straighten cuts i've made with other tools. But you can get buy with a jigsaw, too.
safety: you will need earplugs, safety glasses, and a plan to minimize the amount of dust breathed. Warm weather and climates are great for woodwork because you can let the breeze carry away the worst of the dust.
read read read....about others' project builds, many times folks will discuss their successes as well as what they did wrong or mistakes made
Have you considered building a sonotube subwoofer (not sure what you had in mind) these are super easy if you can cut circles...since normally there is no bracing required.