Displaying a mouse on all players screen is pretty trivial. Frequently sending a packet containing all tiles (coordinates and numbers etc., not graphics) is easy too.
You can save a lot of work when you use existing netcode libraries, eg. the free light verion of BlitzPlay:
http://www.blitzcoder.com/blitzplay/downloads.shtml
Or try RottNet from the toolbox.
Most mportant, to prevent frustration, make sure your game will work trough all firewalls and things. If you plan a fullscreen game, also have a look at the "coordinated Flip" Code in the Archives (probably in the Misc. section).
You can save a lot of work when you use existing netcode libraries, eg. the free light verion of BlitzPlay:
http://www.blitzcoder.com/blitzplay/downloads.shtml
Or try RottNet from the toolbox.
Most mportant, to prevent frustration, make sure your game will work trough all firewalls and things. If you plan a fullscreen game, also have a look at the "coordinated Flip" Code in the Archives (probably in the Misc. section).