The director cant hold more than 15 directorshipof public compaies. However he can hold any number of directorships of pvt ltd co's and section 25 companies. the directors liability is limited to teh extent of the amount paid-up on the shares held by him.
The directors are divided into rotational & non-rotational directors. Rotational dir means dir's whihc are liable to retire by rotation at teh AGM held every year. As per section 255 atleast 2/3 of the directors shall be rotational directos and as per section 156 1/3 of the total rotational directors shall retire by rotation
refer section 254 & 257 for more details on appt of directors