We have lived aboard our boats for the past 24 years. Sailboat until 2004, now a power catamaran.
There's a lot of sticker shock with owning a power boat, and I'll try to answer your questions, though please understand that there are so very many boats out there that it behooves you to do a lot of research for yourself. However, here goes.
I notice that you are in Philadelphia. That means, I assume, that you would be using the boat during the spring and summer months, and hauling the boat out of the water for the winter.
Type of power boat. I really, really, encourage you to lower your sights to a boat more in the 35 to 40-foot range.
Then, there's defining what kind of boat you want. Do you want a trawler - maximum speed is usually about 12 knots, usually more like 8 knots. Our power catamaran falls into the "trawler" species, but because it is 34' long, and is very light, it cruises at about 12 knots. Fuel consumption is calculated at gallons per hour. The averaqe trawler seems to consume between 4 and 8 gallons per hour. (!) At the current diesel prices of $2.75 (or higher) per gallon, that's $11 to $22 per hour, or 3 miles/gallon, approx.
Go-fast boats are a lot more expensive to run, getting about 1 mile/gallon or less.
Keeping the boat in a marina. You should talk to marinas in the area you want to keep the boat, I would guess in your area it would be about $3600 for summer berthing, and electricity is usually metered nowadays. See one local marina's rates Philadelphia Marine Center
Note the difference depending on the boat's length.
Then there's winter storage. That includes haul-out, blocking, storing the batteries off the boat, etc. A few thousand for that.
Bottom paint, replacing zincs. $500 or so. Changing the engine oil every 50 hours or so (4 to 8 gallons, depending on engines, are there one or two, etc.).
Operating in NJ waters, you will have to have a boating safety certificate
I recommend it. Driving a boat is not the same as driving a car. No brakes is probably the most significant difference. Then there's - no road signs, no roads. Understanding navigation aids. Reading navigation charts.
Phew! I don't mean to sound discouraging because I clearly love our lifestyle, but we didn't just jump in with a 40' plus boat. There's a lot to learn.
Now that I've rattled all that off, please ask questions. I think you might be wise to start with a smaller boat - 26' or so.
What do you see doing in the boat? Do you like to fish?
How much comfort do you need? What can't you live without?