If she is still on informal (summary) probation, the most jail time she could do would be 365 days minus whatever credits she still has. On a finding of a violation of probation for failing to complete custody time, the court will likely increase her jail time and place her on a new payment plan to pay restitution.
You need to see the judge and workout a deal with him/her. Tell the judge or your attorney everything that happened. If you wait too long a civil assessment and/or collection agency might get involved. After you resolve your case, make sure the court sends an abstract of judgment to the DMV to remove the hold on your license.
If you're at the Victorville court, I am assuming you were required to show up at Glen Helen on a Friday. Your failure to appear can be considered to be a violation. You need to handle this immediately.
There is not enough information to answer the question. Did he already enter a plea and now the DA is attempted to charge him with another offense arising out of the same set of facts? Or is your boyfriend's attorney and the DA agreeing to an alternate charge for purposes of a plea bargain deal?
It really depends on your record. Assuming you do not have any theft priors and it's a simple petty theft, not a robbery or burglary, an infraction is a likely disposition given the amount of loss. Often, DAs and/or courts will reduce and/or dismiss if you're willing to pay the civil demand amount. I would not pay it prior to working out an agreement.