Bill,
Momentum could be two things,
1. as a tank starts and stops there is a lot of mass to start and stop as well. Real tanks kind of bob a bit when they start and stop, a feature that some boards can replicate.
In addition to the above with the Tamiya battle system when a tank is shot it loses a portion of its overall speed to replicate damage.
The repair feture although used in battles by usually specific vehicles like trucks etc can be a nice feature to have but on a secondary Tank like a bergtiger or bergpanzer etc. It addds a dimmension to your game so to speak.

Based on what you say I might suggest you wait a little bit for the Taipan board as it will have everything you are looking for and more. Taipan will have WiFi connectivity for reporting tank status and a host of options, cost is targeted for $150 or less but that is not in stone either.
I really hate to say this but currently, right now- today, I would suggest a Clark board as you are fairly new to the hobby and this would be your best bet to getting a lot of bang for your buck.

A week or two from now I would suggest the Taipan for the reason that it will be a solid board that does what it is meant to do and will have options that others just can not match.

Of all th