Smoke ring is caused by a chemical reaction between stuff in the smoke and stuff in the meat (I'm not a scientist or science teacher so I don't really care about the specifics, I just care about the cause and affect), to enhance the smoke ring you can put the brisket on straight from the fridge and start your cook at a little lower temp. I don't worry about the smoke ring since it is only a visual thing and I'm not doing competition BBQ, me and my friends just care about how it tastes.
I love mesquite for brisket but if I'm out my next favourite is oak. Chunks work best for low and slow but if I'm grilling steak or chops I usually soak some chips and throw a handful directly on the coals. Mesquite has a strong flavour to it so don't go overboard with it to start next cook try 3-4 chunks and increase a chunk at a time till you learn how much you like.
The greater the temperature differential between the meat and the cooker temperature the quicker the temperature rise in the meat will be. That is why the temp shot up in the meat so fast and one of the reasons that the temperature rise slows down the closer you get to your finished temperature.
For years I cooked bbq without any temperature probes I just went by feel and eventually experience and I hardly ruined any meat. We did eat some late dinners though. I think a lot of people over think the whole process and end up screwing themselves up.
Hope this all helps and isn't confusing.
