Okay i have finally decided to make an E Bike. I currently have a Giant Talon 27.5
Talon 27.5 1 (2015) | Giant Bicycles | United States

I only ride off road Bike Packing, and mostly long STEEP trails usually about 30-60 miles sometimes over a couple of days.
I have been doing a bit of research and decided to get a Mid Drive with a chain gear reduction unit by GNG
GNGELECTRIC---Electric bike conversion kitElectric trike kitHub motorGas bike kit - 60V650W (brushless)

and I have a couple of questions....

1: What kind of battery should I get for this style of riding? I ordered the 48v 450W unit but it can go up to 1000W
2: Is there a way to re-charge in the field? maybe solar or Re-Gen (adding a hub motor for the re-gen)
3: Is there a way to reduce the gearing even further on the GNG unit, and would that be a smart decision (speed is not a concern to me)

Any input is very much appreciated, thank you all in advance.