Couple questions getting your authority

When looking at some of the required info when getting your authority I see they ask for your truck's vin#.

I'm curious if there are any issues changing the vin # once your authority is active? I'm planning to run a hotshot truck.. At the moment I have a F350 single wheel for personal use. I originally intended to start out with this truck, but but have since decided against it..

Instead I'm looking at picking up either a F450 or 550. I don't have my replacement truck yet but is it possible I can start the process with my current truck then update the Vin# before my tags are issued?

2nd question is on factoring. Is everyone pretty much using factoring companies or will brokers pay fast enough it's not needed?