Advantages to ether net/sharing on electronis?

Ok, so I've got a few questions about ether netting my electronics and thought maybe someone on the site could give me some pointers and help.

1. I'm using the Navionics Platinum package on both of my Hummingbirds. I have a 999 in front and an 1198 on the console in back. Can I buy one upgrade package and download updates to both graph SD cards for the next year or do I have to buy a package for each fish finder?

2. Has anyone compared the Navionics against the Hummingbird Lakemasters program? I see that Lakemasters is now out with a V4 for the SE, what is the advantage to that system over Navionics/Hot Maps?

3. If I Ethernet my graphs, do I still need two mapping chips (One for each graph) or can I use just one and share between the two?

4. I have the cabling to do the ehternetting, can you do it by yourself or does it need to be done by a certified person to maintain warrantees?

5. With the graphs I have, can I use the self mapping options on the new Lakemasters program or does it require the newer Helix models?

Appreciate the help guys.

1. I'm using the Navionics Platinum package on both of my Hummingbirds. I have a 999 in front and an 1198 on the console in back. Can I buy one upgrade package and download updates to both graph SD cards for the next year or do I have to buy a package for each fish findnd?
I don't use the Navionics update product, but pretty sure you have to buy an update package for each card.

2. Has anyone compared the Navionics against the Hummingbird Lakemasters program? I see that Lakemasters is now out with a V4 for the SE, what is the advantage to that system over Navionics/Hot Maps?
If the lake you fish is mapped HD with Lakemaster, you will have more features with Lakemaster.

3. If I Ethernet my graphs, do I still need two mapping chips (One for each graph) or can I use just one and share between the two?
You cannot share mappinng chips with your units.

4. I have the cabling to do the ehternetting, can you do it by yourself or does it need to be done by a certified person to maintain warrantees?
Just connect them up and find the Ethernet manual on Humminbirds web page to learn how to set up the units .... No big deal....You should be able to do it yourself.

5. With the graphs I have, can I use the self mapping options on the new Lakemasters program or does it require the newer Helix models?
You will be able to use the Autochart or Autochart Pro PC based programs to create your own maps, but the Autochart Live product is for the Helix and Onix series only.

Thanks Bob B. The lakes I fish are listed as HD lakes on the website.