I need help installing my new GPS

Just bought the Lowrance 3600c iGPS unit and need some help installing.

1st - What type of screws should I use to fasten the gimbal bracket to the deck of my boat? Somewhere in the manual I thought I read to use wood screws????

2nd - My unit only has GPS functions. My main cable for the back of the unit has 3 wires coming out of it. One says it is the NMEA Data Cable.....do I need this....I don't think I do. Another is the NMEA 2000 Power Cable.....do I need this? The other is the Power Supply Cable which I believe is only one of the three that I need. What recommendations do you have?

3rd - I bought the Navionics Premium East lake software for the lakes in KY and IN primarily. However, the manual says that I can save waypoints, routes and other things like that. Does the system have internal memory or does it save that onto the Navionics chip? Just curious.

I'm sure I will have more questions but that is it for now. Thanks for any help.