Not at all. That was more of a warning from me to you that I might miss something you asked 
Regarding of the capabilities of the 7w laser… I’d say 1/8" or 3mm plywood is about the thickest it will do for plywood. It can go thicker on regular wood. It has more to do with the layers of glue than cutting through the wood.
CO2 laser are definitely more capable for both thicker cuts as well as different materials. Diode lasers have issues cutting some materials due to the wavelength of the light.
But to say that a 7w laser can’t cut plywood would be wrong. It takes a few trips around the design, but it’ll get through. Trying to cut through the thicker materials is sometimes possible, but what you find is that it takes more practice to get the setup correct for those thicknesses.
GRBL is the firmware that runs on the controller. Just like Marlin on most of the MPCNC machines. The difference is GRBL doesn’t support LCDs and simply takes the gcode commands direct from the USB port and turns them into movement on the machine. CNC.js is just a web-based app that can run on a computer and sends the gcode commands out to the grbl or marlin based controller.
You would still use inkscape or some 2d design software to create a vector drawing (typically svg). Then you’d import that 2d design into estlcam to create the gcode (CAM part) that then gets sent to the machine. An alternative to ESTLCam for the CAM software is lightburn. Lightburn has the positive in that it is designed specifically for lasers. It provides other functions that allow you to import raster (jpg) images and to do greyscale burns with the laser to engrave images instead of just line art. There’s others on this forum doing a TON with the cheap little diode lasers.
My link and another post on the same forum with a lot of examples:
and this is the one that inspired me to get the more powerful laser:
My laser thread has a link to one of my youtube videos of my cheap laser. From there you can find some of my other laser videos. One is a time-lapse of the build of the machine itself.
Feel free to ask more questions. I enjoy talking about this stuff. If you ask a question I don’t know, I’ll tell you, or research it and then tell you what I find