I'm not going to go so far as to say you do not have to pay. The law provides for this remedy (42 Pa.C.S.A. Sec 8308) and actually requires the retailer to give you 20 days to respond and pay. They cannot bring civil action if you do and they must provide you with written release from any further civil liability. They can bring a civil action if you don't and request in addition to the penalty attorneys fees and court costs. Its up to to decide whether they will - see my colleagues answers.
Paroled without petition - When someone is given a county sentence the Judge is in charge of Parole. In most cases, like here, the Judge will say this so the defendant can be paroled by County Probation and Parole without having to get the Judge's approval first.
Generally speaking posts on Facebook or any other online site, if able to be authenticated (shown that you in fact posted it), could be used against you in court if relevant to your case. You must always assume anything you say, write, post etc... Could be used against you. So carefully consider what you are about to say/post before doing so.
If the DA attempts to withdraw the deal nothing is going to stop him from doing so. Moreover most deals like this are contingent on having all the information available to him. I'm not sure the "new law" being referred to without more information, but if your guidelines call for more time or a mandatory not contemplated by you deal - there's a good chance the Judge wouldn't even accept the plea anyway. On the other hand, your attorney could take an open plea and ask for the "benefit of the...