The federal sentencing guidelines are complex and consider a variety of factors in determining what your guideline range should be. In terms of criminal history, the guidelines only score convictions, not arrests. However, the court at sentencing is free to consider your arrest record in determining the appropriate sentence.
The amount of time the person can be sentenced to will depend on a variety of factors. You say that he is on parole. Are you referring to supervised release? Or are you referring to parole in the State of Texas? This person is going to need a good attorney regardless of how you answer.
It is very fair to assume that this matter is indeed "super serious." Given that the U.S. Marshal's service has placed a hold on him, he could have pending federal charges. Your friend needs a good lawyer. This is especially so in situations such as this. When a defendant is taken into custody by the state and then later charged by the feds, the attorney representing the defendant at the federal proceedings must take extra steps to ensure that the defendant receives all his prior custody credit....
With a 60 month sentence, your husband will receive 235 days of good conduct time, which is approximately 8 months. Assuming he receives the whole year off for RDAP, he could be release in January or February of 2015 to a halfway house.