I see the marks and the burns. I had an issue with marks and did not see how they were caused originally. I had not taken sufficient care to square everything properly. Undoing the machine and rebuilding it from scratch with proper regard for squareness (and a lot more insight into tramming errors) left me with a machine that cut perpendicular to the workpiece. Belt tension is crucial too. Both Y rail belts should be equal in tension or they can cause uneveness. If you can match the tension in the X rail, it helps to prolong their life.
The burning of wood is something that you learn as you cut more wood and different types of wood to see how it reacts to being machined. When you are running a job, do not forgot that in Carbide Motion there is a page which will allow you to up increase or reduce the feed speeds while the job is running.
The pocket toolpath is good for surfacing and I ensure that my workpiece size is increased by the amount of stepover required to ensure that the cutter extends over the edge by at least 50% of its diameter so it does not leave a curved corner to remove. I take small cuts (0.2) and do not worry about the time it takes. Cutting easily and without stressing the machine is helpful. The way to preserve the sharpness of tools is to treat them well.