I agree with you that reliable is better than fastest possible, especially in a home shop/hobbyist situation (which is where I am).
Sorry on a couple of levels. I don’t know that I’ll be of much help on the specifics of your machine as I have no experience with it. If you purchased it, is there support available from the vendor? They should have a good idea of the capabilities of the machine. The velocity and acceleration values should be very close, if not exactly the same, regardless of the software tools being used to drive it.
Where do the steps per mm numbers come from? Do you have imperial leads screws that cause the calculations to have decimal components? The belts and metric lead screws I’m used to tend to end up with round numbers for steps per mm.
In my (limited) personal experience, lead screws are slower than belts (unless you’ve got ball screws, which I’ve never actually implemented). 2000 and 3000 max rate seems quite high to me, but it’s not clear whether the units are mm per minute or mm per second. Also, you’ll eventually want to match your MaxTravel to the actual sizes of your axes, but that can wait until you’ve got things moving.
The control board I used with the nema23s on my old phlatprinter didn’t allow for current adjustment, so I don’t have experience tuning for those motors. As long as you’re within the current/amperage range for the motor (see the manufacturer’s data sheet) you shouldn’t be in danger of damaging them. If they’re getting too hot to touch you’re running the current too high. If the drivers get so hot they pause to protect themselves, you’re running them too high - but adding heat sinks and active cooling (a fan) can mitigate this. If things are mechanically well aligned, lubricated, and move smoothly but you still lose steps, you may want to increase current as long as you’re not hitting the “too high” markers identified above.
As far as the spindle is concerned, my advice is going to be even more generic. The spindle control I’ve used has been pretty basic - either relays for simple on/off, or the V1 PWM control solution which ran the PWM signal on the “Spindle Enable” pin on my shield. I know there are lots of options, including things being reversible, and safety interlocks, overheating protection, etc… I’d need to rely on the documentation for your spindle controller (VFD?) provided by the vendor. Here again, they would be the experts I’d turn to for support with their products.