Alot of these problems take care of themselves as you continue to have consistent expectations, and more and more of the class gets behind you. In order to make those two conditions progress, though, you want to point it out on the scoreboard, but you don't want to start off pointing out who's doing it (gives the obnoxious ones the attention and power they want, and makes the shy ones feel painfully embarrassed). Just by saying, "Almost, but I didn't hear everyone say "Yes!"..." etc... and then give yourself a point (sometimes, in order to keep the +-3 rule going, you may have to pretend you didn't notice...remember, you are in control of the scoreboard. Use it to send whatever message they need to hear). The shy-guys will sit and watch for awhile, until they feel comfortable enough that the majority of the group is doing it, and even then, you'll notice there are BIG personalities and not-so-big personalities, and that's ok. Biff always tells us to Praise, Prompt, and Leave. Meaning, as you're walking around the classroom, praise the ones who are giving you what you're looking for, prompt the ones who are not, and move on to somewhere else in the room. Don't dwell on it.
Eventually, you may need to move on to more 'industrial strength' methods, but at first, don't sweat it. Also--very important-- use Biff's class scoring method to sort out how many kids you have that are these 'outliers' or 'fence sitters'. As you 'let it be' for the first month or so, go through and re-do your scores for this every week or so, so you can see the numbers change and you can tell if there's real progress or not. It really helps you focus on the individuals in the class, as I think it's harder to judge the progress of 'the class' as a whole entity, versus the progress of individual numbers of kids.