DVP = drop volley profit. Basically you volley tuts with another player until one of you gets however much money?
Dvp is basically hiring a tutor back and forth with another player to make money. You make ~1.58% of the hire value every time a tutor is hired away from you, and the tutor price rises by 5% of the hire value with each hire - because of this, it's better to have a good amount of cash when giving/receiving dvp, since you need to volley a tutor to about 6x the price of the actual profit ie. to make 10b, you need to volley a tut to 60b. Whoever keeps the tutor in the end is the one giving dvp since they're losing that 60b. People sell various items for dvp, most common being a chibi for 1-2b each or a bento for 50-70b (prices fluctuate from person to person). This is the most efficient way to gain cash for upgrades as a smaller stat player. Hope I covered everything.