[G4] new mac user:questions about memory and more

[dapper dan]

so i have the plate off the bottom of my mac g4 867mhz powerbook.question: 
how are the memory modules removed? there must be two since i have 256 mb 
and the top card is 128mb.

how can i tell if i have a cd burner?

did these competers come with wifi? if not,where would a card be installed?

and i cant find any antivirus software? where would i look?

thanx
dan