Going by one of the BW specials, Forrest is now officially the gym leader (he nearly lost the position as well as the gym itself due to a clerical error. Brock had to save the gym for the third time as a result). We don't know anything about Viridian Gym though. Heck, we don't even know which gyms lost their gym status, only that three got shut down via PIA inspections around the time Misty was forced to resume gym duties by her sisters. We probably would have gotten some answers to those questions had they actually COVERED those bits during Ash's trek through Battle Frontier instead of wasting time on other stuff barring the objective.
And yes, it's definitely implied that Kanto has more than just the eight gyms in the region. In fact, by my count through Gary and that Otoshi guy, maybe that other trainer Jessie nearly stole badges from before James and Meowth blew her cover as revenge for stealing the badges from them, there were possibly 27 badges, 19 bare minimum. Heck, not just Kanto, most of the regions that had gyms generally had more than eight (or nine in the case of Unova due to the whole version-exclusive gym thing) with the possible exception of Johto. From what I can gather, there were nine in Hoenn, about 11 for both Sinnoh and Kalos, and about 15 in Unova.
As far as the gym leaders, Johto and Kalos had the best gym leaders, mostly because they were shown to be very skilled at battling, and without making Ash look incompetent either, not to mention Ash actually EARNED his badges there. Kanto is second-best, since while the Gym Leaders are indeed shown to be forces to be reckoned with, Ash did end up getting half of his badges without actually winning. Sinnoh's gym leaders were sub-par, but at least were able to put up a fight with Ash and be a challenge (although on the downside, they made Ash and Pikachu look incompetent in the process despite Ash winning against a Regice not too long before), and Hoenn and Unova are tied as being the absolute worst of them, thanks largely to their being easily manhandled by rookies and, in the case of Unova, probably the worst incarnation of Ash ever (second-worst if we go by Sun and Moon). The Elite 4 were generally depicted well, with the only real exception being Kalos, since they ironically enough may have been made incompetent compared to the gym leaders slightly. Note that Alola does not count since they don't have gyms.