Properly Attach Cabling To Joists

I am also in the Northeast and have had to tackle this type of situation a few times. There are several ways to attack it.

In your case, the best solution, but unfortunately the most expensive would be to use an open cell foam kit to fill the joist bays. They are fairly easy to use and give you about an R-4 rating per inch. They are a two tank kit with a hose and wand. Here is an example product: Touch N Seal 1000 Kit Open Cell Spray Foam Insulation

These type of kits start around $400, depending on the square footage and depth required.

A cheaper method would be to use 24 inch R-19 unfaced blanket insulation cut to your custom widths. You can use wire springs to hold it in place and keep it from falling. I would then cover the entire area with 4 to 6 mil plastic, stapled to all the joists. Tape the joints, if any. Moisture should not be a major problem since you have already done what sounds like a good job sealing the dirt floor. In the summer months, some ventilation in the crawl space will also help avoid excess moisture.

Rigid foam glued to the foundation walls would also help if the area is fairly air tight. If there is free air flow, insulating the brick walls would be a waste of time and money.

Yes, bringing the crawl space into the conditioned space is generally recommended as a way to prevent crawlspace moisture problems (I assume this is what you mean by encapsulate).

This means:

1. sealing vents to the exterior
2. sealing the dirt floor with polyethylene sheeting (at least 6 mil), or concrete
3. creating vents between the living space and the crawlspace (ideally supply air to/from the space with HVAC ductwork), and
4. insulating the interior side of the crawlspace walls on (not necessary in climate zone 1 or 2; and preferably with board foam or spray foam because fiberglass doesn't do well with moisture).
5. probably a good idea to remove existing floor insulation

This will prevent humid outside air from coming into the crawlspace and condensing on cold surfaces, and prevent/reduce moisture from coming up through the dirt floor or walls. Your AC will also deliver cold air more effectively. Good site drainage is also key.

There are many good references on how to do this properly:

http://www.housingzone.com/crawlspaces-vent-or-not-vent

https://buildingscience.com/documents/bareports/ba-0401-conditioned-crawlspace-construction-performance-and-codes