There's nothing to worry about. With that Diablo blade, you'll be done in no time. Just make sure to square up the saw before you start the real cuts.
I'm using 96t 12" blades from Frued/Diablo, and due to lack of cutting grease I use WD40, works perfect. No need for a high performance miter box but I already had a 12" blade one with a sliding arm. -Ronald
Stumbled upon open build trying to teach my self how to build a CNC. With that said I do a lot of woodworking as a hobby. I would recommend going with a 10" saw miter saw. Any blade will be from 50-100 teeth will work. They also sell an aluminium cutting lubricant that you can spray while cutting helps with finish and prolongs tool life. Sliding miter will be beneficial if you need to cut over 6" at 90 degree or 3.5" at 45". As for making repetitive cuts you can simply clamp saw down to bench and clamp a stop block at proper distance. Simple trick to dial in exactly is set stop a few thousandths longer than desired cuts and use post it notes as shims to dial in. They are approximately .003" per sheet. Hope I helpled. I have found this site to be invaluable.
I cut a lot of extrusion using a standard Craftsman miter saw equipped with a cheap $25 non ferrous metal cutting blade I got on Amazon. I don't use any kind of lubricant. It cuts well, has lasted through hundreds of cuts, and leaves a nice smooth end. However, it is noisy, and it blows aluminum shavings all over. I have a Masonite hood built around and over my saw, with a 4" dust collection port at the back, and it still blows shiny confetti all over the corner where the machine is located. Oh, well, just a minor inconvenience to vacuum it all up after. However, I usually touch it up using my table saw sanding jig to ensure the ends are square and smooth. I cut the pieces a millimeter or so long, and sneak up on the final length. See A Slick way to Square up V-slot and C-Beam for details. MG