ubuntu 11.04 - internet, opening terminal, restart and shutdown

i wish to know what files in operating system of ubuntu 11.04 are required to be set 755 or 644 in (rwx rwx rwx which is eq to 777mode ) in order that internet either mozilla or firefox should work, a terminal should open and restart and shutdown commands should work? for one of my work i wish to have every file of ubunut 11.04 operating system as rwx------ or rw------- i.e. 700 or 600 mode only i.e. they work only from root not from other group or users.