Adding another Head Unit (fishfinder)

[EZM]

Does anyone who has experience have any cool ideas they used when adding another fish finder onto thier boat? Here are some of my questions and/or "nice to haves". ( I have a HDS 5 Lowrance equiped with a Navionics Chip)

1) If I add a new HDS 8 (and make it the "main" unit at the helm) will it retain the waypoint data from my HDS 5 or do i have to start all over? I want the bigger screen at the helm so I can manuver the boat to the drops and ledges I've marked. I would then wire the HDS 5 as the "secondary" unit.

2) Do both units use the same transducer effectively (in other words) - if I set up the 8 (main unit) to have 3 screens (downscan, chart and sonar) and I want the 5 (secondary unit) to do sidescan and sonar - does the transducer effectively handle all of this data without "lag".

3) How hard is it to make the secondary unit "portable" - in other words I'd like to run some wires to the bow and some to the stern - so when I'm trolling a big lake and both fishermen are in the back I can have both finders back there and more views to look at on different screens AND, alternately, when casting It can be used up front by itself? Has anyone done this? any suggestions or issues?

Thank-you in advance for your opinions / tips.