It isn't not allowed it would just be awkward.
In many jurisdictions, marriage between cousins, in some places even between First Cousins, is permitted.
Yes, a cousin-in-law is considered a relative by marriage, not by blood.
If it was legal in Colorado, it would be in Kansas.
yes
A "cousin by marriage" is not your blood relative. That would be accepted in most jurisdictions but you need to check the laws in yours.
yes
I never heard of that. It's my understanding that you can marry a relative closer than your first cousin.
Yes, your wife is a relative by marriage, and is considered to be your closest relative.
It is legal to marry a second cousin in California. It is not legal to marry anyone else in your family. California also allows first cousin marriage.
Depending on local and state law, it is a marriage to a blood relative that is a cousin or closer. Some states allow marriage between first cousins, but the Federal Govt still frowns upon it...
Your cousin by marriage.
A cousin by marriage is someone who is related to you through marriage, not blood. They are the spouse of your cousin, or the cousin of your spouse. They are considered part of your extended family, but not directly related to you by blood.
It may cause some deformities in the child. You are allowed to marry anyone beyond your cousin though in the US