The paladin hardly adds anything exept for taking hits. Once you got some good pvpgear you can easily take the hits on your shamans and ask a healer to join you.

The partyleader of a premaded party who joined last get's leadership(not 100% sure about that). So asking the healer you bring with you to join when the pop up comes and notify you when a BG allready started allows you to wait untill the last 20 seconds to join and be sure you get leadership.