I'm no expert, but both states are going to want your $, so if you have a current Nebraska address, I'd get temp tags in Colorado and register in Nebraska. Kind of depends on how long "temporary" is. Or register here, keep your Col tags when returning to Neb. until renewal time, if you can get away with it. Depending on Neb. reg's, you could end up paying another sales or use tax there.
In most instances you pay tax and license in the state where you reside.
A person living in Nebraska is typically referred to as a Nebraskan.
One year
Fro the shops, yes.
Yes
To establish residency in Colorado, you generally need to be physically present in the state for at least 12 consecutive months. This includes demonstrating intent to make Colorado your permanent home, such as obtaining a state driver's license, registering to vote, and paying state taxes as a resident.
No
Florida has almost 19 miillion resident compared to 5 million for Colorado.
Not without being a resident of the state, and, to be honest, you wouldn't want it anyhow - get pulled over in any other state with Colorado plates and/or a Colorado license, and they're going to come up with an excuse to search your car, thinking you have weed in there.
Yes
If your Massachusetts license allows you to operate a motorcycle, you should not need to get a Colorado license because you are only a temporary resident.
No, it is a federal crime. You are crossing state lines with a handgun.