Looks like you just fell in the rabbit hole down to the feeds and speeds Wonderland
This is admittedly the hardest part in the CNC learning curve, and for me it was extremely confusing at first. I tried to make (some) sense of it all in this chapter of the ebook.
Since Fusion360 is a very generic CAD/CAM tool, the defaults feeds and speeds that come up in the toolpath window are also extremely generic, and steered towards very difference CNCs.
CC recommended settings will be a good starting point (especially in the latest releases, which introduced very sensible defaults), but I think it’s also worthwhile to spend a little time to get a basic understanding of how to adjust your feeds and speeds when your usecase does not quite match the available combinations of endmill/material available in Create or elsewhere.
I won’t even try to summarize this here, because…well if it took me 20 pages to scratch the surface of this topic in the ebook, I can hardly make any sense in a few sentences
However here are a few pointers related to your questions:
That’s because surface speed is directly linked to spindle speed via the diameter of your endmill (that Fusion knows about). Surface speed is just the linear speed of the outside of the flute, so if you spin the tool faster, it increases. You don’t need to care about surface speed for now, what you should enter are spindle speed and cutting feedrate(s) (and then depth of cut etc in other tabs). Check the feeds and speeds chapter I linked above to see how feedrate, spindle speed, and cutter type are derived from each other.
This will get clearer after you read about that relation between RPMs, feedrate, and endmill flutes.
At least they are the easiest to use at first, and yes they rock for cutting aluminium. The main reason is that chip evacuation is easy due to that very wide (and single) flute, so the risk of jamming the cutter with chips is very low, hence the risk of melting chips in the flute is low. However, you need to adjust feeds and speeds versus e.g. the ones that would be used for a three-flute endmill.
No, that’s definitely not the limit, but this “10.000RPM” attractor in CC is (probably) to make the feeds and speed achievable both on a Nomad and a Shapeoko (the Nomad max speed is 10.000RPM, while the CCR min speed is not that far from 10.000). Again, after you read about feedrate vs RPM, you’ll be able to tweak that very quickly (basically, for a given endmill if you multiply the RPM by X, also multiply the feedrate by X). Generally speaking, for aluminium you will want to go for higher RPMs.
All of this being said, I’ll let @neilferreri comment on that Fusion360 file !