Assuming that the burglary was not committed with a firearm, which would kick in the 10 20 Life law, the minimum sentence under the guidelines scoresheet would have to be calculated. Without knowing all prior convictions, it is impossible to calculate from your information. Also, since you indicate a VOP pending. That is a separate case that would be separately scored and there is an enhancement in the vop scoring. In Florida, the State Attorney's prepare the guidelines scoresheets and routinely give it to the defense with their plea offer. You could wait to see what they prepare or give your attorney all of the details and he/she can compute the scores.
Regarding possession of the firearm during the commission of the felony, if it was not discharged, there is a mandatory 10 year sentence with no reduction for gain time, that is day for day. However, he may be looking at a much higher sentence which includes the 10 year mandatory minimum. Again, depending on his guidelines minimum, the state could run the charges and counts consecutive, meaning one after the next. He really needs a competent felony trial attorney.