You will receive separate sentences from each county. With regards to probation supervision, you will likely be transferred to have all probation/parole supervised in the county where you reside. That way you will only have 1 probation officer to see. I would suggest that you retain an attorney to make sure both cases are handled correctly and that your logistical situation is handled correctly.
There are currently challenges in the Pennsylvania appellate courts regarding this very issue. The argument is that someone pled guilty with a certain registration requirement, and now is subject to a far greater one. You should consult with an attorney and closely monitor the outcome of these challenges.
You should certainly consult with an experienced attorney. If you were convicted or pled guilty to the charge, then you are not eligible for expungement in Pennsylvania. Only an experienced attorney can review the case and give you a firm opinion on whether you are even eligible.
A motion for return of property needs to be filed in the Montgomery County Court of Common Pleas. This action will force the police to return the items if the Judge signs a court order. Unless this is done, they will continue to give you the run around.
Depending on when the conviction occurred, your son may be able to file an appeal on the case. He can consult with an attorney who handles cases in New Jersey to see whether he has any valid grounds for appeal.
Your first DUI may have resulted in ARD and therefore it would not be on your criminal record. It will appear on your driving history and the DA's office will be aware of it. The law in PA has a 10 year look back period so you will be treated as a 2nd time offender. You should hire an attorney immediately because the penalties are significant.
In Pennsylvania, a summary conviction can be expunged from your criminal record after you have been crime free for a period of 5 years. So based upon your question, you have 4 more years to go until you are eligible for expungement.