Keep Circulating the Tapes: It depends on which country you live in. The U.S. only got six VHS tapes (with three shorts per tape), or the equivalent of three full episodes. However, Europe got more on VHS, and also got three DVDs. No matter the country, however, there are still plenty of episodes not on home video.
Really, everyone at some point except Rafiki. According to IMDB, Timon had four different voice actors over the course of the series (including Quinton Flynn), and even Pumbaa got a replacement voice actor at one point.
Averted in many foreign dubs, when almost everybody retains their voice actors from the films in the TV series. The only exception to this was in the Japanese dub, as Pumbaa is still voiced by Atomu Kobayashi (a theather actor and his original voice actor in the films) in the first seven episodes and replaced later with Hiroshi Hatanaka, who also voices him in the Kingdom Hearts games.