CV 3 is just a matter of taste, just depends now who slow you want it to accelerate. If you set it high say around 15 or more, if the wheels or track is dirty the engine can stall. If I change CV 3, I use around 6.
Cuda Ken
I hate Rust
Take a look at CV3 also, it could be the momentum got set very high so it's just taking a long time to ramp up to enough power to move the engine. I believe NCE decoders ramp up right to the amt needed to move the engine, then apply momentum from there, but most decoders just slowly apply power based on CV3.
The answer is yes. Do you have the manual that came with the loco's?
If not what brand and Model's do you have? There are a few different settings that can affect the start speed. Also there are beginner DCC guides available on this site I recommend you read. It will save you a lot of grief.
Springfield PA