Hi,
I also use Autloeveller, and at the time I paid 20GBP as shareware/donation, but note that it's now free. I'd be lost without Autoleveller.

I use double sided tape to hold the PCB blank down with two 1.5mm pins as alignment dowels. I find that the double sided tape does not tend to pull any bows
or warps into the blank whereas clamps, bolts or screws tended to do so. I use 10mm polycarbonate as a spoil board and the double sided tape adheres well without
being overly difficult to remove. As CoD commented, it's what works for me.

My spindle does 24000rpm and I set the feed rate at 600mm/min. Long continuous runs at 600mm/min cause a borderline overheat of my steppers so am not tempted
to go faster. My new build mill has 750W AC servos on each axis so will push the speeds up BIGTIME when its finished. I'm thinking that 3000-5000mm/min will be
doable......can't wait to try it out!

I use, mostly, Kyocera-Tycom 0.2mm 45 degree engraving tools, approx $4.00USD each, for fine trace boards and use Kyocera-Tycom 0.5mm two flute endmills, approx $4.00USD each,
for through hole boards and SMT boards down to 0.6mm between pins, so SOIC and bigger.

Craig