I have an 1198 and 898. If I buy the Ethernet cable, when you plug them in do the way points on 1198 show up on the 898, or do you have to go through the menu? Also I dont have a map card in the smaller unit, if I was to get one do I have to have the same chip in both?

When the two units are linked with an Ethernet cable you will be able to share data only (waypoints) from either unit. No need to go into menu/settings.
You can utilize different chart cards (i.e) lakeMaster in one and Navionics in the other.

Ethernet will display the waypoints of one unit on the other in a different color. It does not write the data to the other unit;s memory. Default setting is Share, so you don't need to do any settings.

Those units will not share mapping with any connection. If you want additional mapping other than the included ContourXD on both you need two map cards. They can be Lakemaster or Navionics or a combination of the two.