Need to shadow a dentist first, preferably a general dentist as some school require verification. Also you can start preparing for the DAT and eventually taking it when you feel comfortable. Other than that, everything else looks good, assuming a decent DAT score, you have great chances at most dental schools.
volunteer at a dental clinic or anything else with dentistry
shadow general dentists
even though I think pre-dental clubs are time wasters, you should join one since nothing on your EC is dentistry stuff
hard to do but you can try to get a dental research project (could be microbiology, clinical at the dental school, or easy survey type projects)...contact some researchers...to be honest, any research will do
Take the DAT whenever you're ready...this application cycle is over...next one opens in like June 2014...try to take DAT before then just because you probably have a lot of free time now and to make sure you're in the first batch...you can take it later if you want to...the DAT is a lot easier to prepare for than the MCAT
M.PH is a personal thing...I wouldn't do it but if you want to, go at it.