I'm very interested in how you're doing this with a simple circular saw. What kind of blade do you use? Do you have to use painter's tape to reduce splintering?
What will you plan to do for doors? I made some simple shaker doors on my table saw. For a first time, they weren't bad...but I already have thought of ways to improve. Will you build your own doors as well?
Where do you buy your plywood? Any preference as to oak, maple birch?
Sorry I have so many questions, but your project is inspiring and I want to do the same!
I don't have a special blade for my skilsaw but it is less than a year old. If you cut from the backside, i.e. the good face is on the bottom, their is very little splintering on the face side since the skilsaw is cutting on the up stroke. I normally am not worried about the backside splintering because most of the time it isn't visible.
I do plan to make the doors and drawers. The doors will be simple shaker style using solid oak frames and 1/4" plywood panel insert. I will make most of those parts with a tablesaw. I haven't decided what I'm going to make the drawers on. I have a jig that I use to make box joints on my tablesaw easily so I'll probably do that although I do have a dovetail jig for a router as well. It is more finicky to set up but you can make half blind dovetails and such.
I live in a rural area and the only place to get cabinet plywood in a 150 mile radius is at Menards. I have used Birch before but Oak was about $10/sheet cheaper when I started this project so I went with that. I think it is harder to stain than Birch using off the shelf tinted stains from a big box store and get the desired color. So I take a piece of it to my local Sherwin Williams and they custom mix up a stain to the exact color I want and apply it to verify it. They are also very price competitive when it comes to stain. I also used laminated plywood instead of MDF core plywood since I'm using a lot of pocket screws on this project and they hold better in laminated versus MDF core.
The one drawback to working with plywood is the top veneer layer is very thin and easy to sand through if you aren't careful. If I'm just sanding the plywood face, I start and end with 220 grit sandpaper. If I have to make sure a hardwood edge is flush to the plywood veneer layer, I start with 120 but go carefully and quit just as soon as if feels flush to my fingertips.
Working with plywood is a super fast way to build furniture and it is much lighter and easier to work with than trying to make everything out of solid virgin wood.