Reading of a will is something that happens far more in fiction than in real life. It is not required.
The authority of an agent/attorney-in-fact under a Power of Attorney ceases when the person who granted the power passes away.
To understand what should happen, I would suggest that you do a search on terms like "Maryland probate process." You will come up with websites like:
http://registers.maryland.gov/main/
http://andalmanflynn.com/practice-areas/probate-and-estate-planning/