Hi,

Yes you can reverse the direction by swapping any two of the three phase wires. Most VFDs allow you to swap direction programmatically as well. That would allow you to
ensure that FWD on the control panel is rotating correctly for right-handed tools.

5 seconds is a generous ramp up time. It means that only modest currents will be drawn when accelerating up to speed, but more importantly diminish the voltage surge that occurs
when decelerating. I have mine set at 6 seconds....been like that for over ten years. Its enough. If you are doing production and have an ATC the 1 second or less would be common,
but for that you'll want a braking resistor!

1.6A at full speed no load sounds about right. The spindle is an induction motor. The 'induction' part comes from the fact the a proportion of the stator excitation (from the VFD) 'induces' current in
the rotor, and is how an otherwise un-magnetised rotor becomes magnetised. Thus you will need some current, maybe 0.5A, maybe 0.8A to magnetise the rotor and the balance to overcome windage
and friction.

Even water cooled spindles do not like being run at part speeds. If you were being conservative you might limit the slow speed to half rated speed (12000rpm), that would go a long way to protect your
spindle. You could reduce that to 1/3 or 1/4 speed (8000rpm-6000rpm), but be aware that if you take heavy cuts at these low spindle speeds you risk damage to your spindle.
I have an 800W air cooled spindle and so I'm doubly careful not to run below 12000rpm....but sometimes I have to. I have a carbide slitting saw, and very useful it is. Its only 0.25mm thick
and 27mm diameter. Being as thin as it is make for a very VERY narrow kerf, but also make it very fragile. I doubt it would survive the centrifugal forces of spinning at 24000rpm, so I run it at 6000rpm.
I don't use it a lot, and very carefully and quietly when I do, and for the brief low power use at 6000rpm has caused no harm to my spindle and surprise surprise the slitting saw is still intact five years
after I bought it!!

Craig