Thanks for your questions.
1. Yes she would be allowed to join you in the UK as your wife if you were married. The general grounds for refusal, of which good character is one, do not apply to family applicants, thus, your partners application would not be refused under the general grounds if you were to marry. The decision is one which is made purely by the UKBA.
2. Yes she would. If you were married.
3. It would be easier for you to marry in the US and then submit an application for her to join you in the UK or for you to permanently reside in the US.
4. In order to marry an inmate in the US, check with the particular prison he is in to see what the policy is regarding inmate weddings. Some may actually allow a ceremony and time alone for the couple, depending on the nature of his crime, his prison record of disciplinary infractions and the mood of the warden on that given day.
I hope this answers your question. If so, kindly click accept.
If you wish to discuss, please feel free to ask further questions.
Edited by INC on 1/17/2011 at 12:49 PM EST