M.C.
I work in insurance and specifically pricing of insurance. Here's what you need to know:
Your insurance rates CAN go up after at not at fault accent. However, in the state of PA, insurance companies are not allowed to charge for not at fault accidents. This means that since you live in PA and have your auto insurance in PA, Erie cannot increase your rates because of your not at fault accident. You will need to provide proof that this was a not at fault accident (sounds like you have a police report). You can go to the Department of Insurance website for PA to see this for yourself (you can google "PA DOI").
Hiring an attorney is not worth it unless there is BI involved (bodily injury). It's a waste of money for $400 on a PD claim.
Allstate is notorious for not paying when they are required to. Your best bet is to let Erie handle and get your money for you. It could be the case that the person who hit you only carried minimum insurance limits and therefore if the cost of your repair/rental exceeds those limits, Allstate does not need to pay and your insurance would have to step in to cover the remaining. If Erie (or Allstate for that matter) gives you a hard time, it'd be worth your time to contact the PA Department of Insurance. If you write a formal letter of complaint, they will address with the insurance company. The PA DOI is very consumer friendly and deal with complaints quickly.
Good luck.