If the V-brake arms stick up too much, your rear rack supports can interfere with the V-brakes (as a friend of mine found out when he built up his Nashbar frame). If you don't have compatible brake levers, as Jtgyk says, you can make the conventional brake levers work using a QBP Travel Agent.

On the other side, the Nashbar touring frame doesn't have a rear brake hanger built in, so you must provide your own. Also the cut in the seat tube is on the front side, so if you're going to put a brake hanger on the seat post clamp, you must pick a seat post clamp with sufficient clearance to accommodate the hanger. I use a Surly stainless steel seatpost clamp and a Surly stainless steel hanger, which looks great but is a bit spendy. I use Avid Shorty 4s on my bike. They get the job done, but don't do it particularly quickly. (To be fair, they have a lot of weight to stop.)