Whew!!! that's a lot to cover with any detail.
First thing is Humminbird's Side Imaging is adjustable for screen scroll speed---that is every Side Imaging model Humminbird has or did have. That means you can use it and get sharp images from near zero boat speed to about 12 mph. Fish at whatever speed you want, just need some movement to scan. It also will show left and right for hundreds of feet if the bottom is flat enough as long as the transducer is not buried in the bottom.
The G2N Helix 7's are linkable to other units via Ethernet, the first generation and G2 Helix 7 are not, but they still do sonar/GPS equally on their own.
360 is more of a sitting still fishing a target after it has been located deal.
I'll add more via PM so I don't get the dreaded Server Error with too many words at one time.