Dennis,

FIrst of all welcome to the site and congratulations on your new boat, you made an excellent choice. While I can't address any of your questions on the GPS since I don't have it I cam tell you that charging your trolling battery through the female connection is a great way to charge the battery; that's how i charge my trolling motor battery.

If you haven't purchased a battery charger yet I'd recommend getting one that has variable settings with a maximum of 20 amps and an overload switch that will turn the charger off when the battery is fully charged. I bought mine from Home Depot for around $70. I also bought two Marinco ConnectPro Plug/Accessory Kits from Bass Pro Shops. I set one up on the cranking battery so I could charge it like the trolling motor battery and used the other to connect the original battery clamps that came with the charger back to the charger so I could use it on a car battery.

Hope this helps.

Tom