Absolutely not, no to the second, and yes to the third question. They want GOOD, INTELLIGENT PEOPLE. If you are working half time, or full time at that, they always take that into consideration. Coure load is also VERY important. The interview is the time to show them what type of person you are and if you should really be in this field.
The reason schools care about stats is simply because they need to know you are committed to dentistry. It's not like it used to be when a 17 would get you in, the environment has changed and so has the competition. I've talked with admissions and they say they have so many qualified applicants they have to turn away just because there aren't that many seats available.
This whole entire website scares some people because people are constantly posting 20's, 21's and 22's. I've even seen some people say they have gotten 24's even though only about a dozen people get a 24 each year. Everyone on here is a nerd anyways and has higher than average scores. You just need to be +/- .5 from the avearge GPA/DAT at the school you are applying to have a good shot. Take what you read with a grain of salt and remember this is a 30/30/30 deal. GPA/DAT/Application. I would even go so far as to say that the app is more like 50% because you are in complete control of what happens. DO NOT SLACK on the personal statements, tell them about why you LOVE this field and will do anything to get in.
If you want to get it, you can and will.