74 chevy radio?

[frog210]

hey guys its me again
i have a question
the previous owner installed a pioneer radio or kenwood
(dont have pics at the moment or truck in front of me)
what i wanted to know is
isn't the radio suppose to keep its memory when the truck is turned off?
I looked at the wires briefly and noticed the previous owner just cut the factory radio harness off and wired the radio in
I noticed that the red wire, yellow wire and orange + and orange - were all wired together?
also how do i wire the antenna?
people been telling me these copper wires in the windshield are the antenna?
I noticed there is a metal tab on the inside where i guess the wires in the windshield connect to it, but how do i connect the radio antenna wire to it?