I am currently creating a Java online/networking version of Scrabble. I've been researching into the best way to transfer data however i've decieded to ask for the best advice on here

1) what would be the most efficient techinque for communicating over a network bearing in mind small amounts of data are going to be sent (nothing complicated) (between two computers not any more)
2) I'm completely clueless regarding security, what methods would i be able to use (preferably in conjunction with my first question) to apply simple yet effective security to the data being sent
3) finally would it then be possible to include support for more than two players (keeping in mind the techniques suggested in q1 and 2
Many thanks for your time guys
tom