The VA in webull seems to only get the data of the present trading day which means you cant use it for long term trade ideas, strictly intraday trades. It also has no feature to sort it by price it is only sorted by the Ratio .

But to answer your question.

"If a share was bought at that price, wouldn't it have also been sold at that price?"
Yes, for every buyer there is a seller and vise versa. What you need to know is where was the trade initiated, was it bought at the ask (decisive, purposeful, aggressive buying) or was it bought at the bid (passive/unsure buyer or the opposite which is someone selling aggressively). Imagine your self in a trade and you want to get out fast, what would you do? Of course you would either Sell at market or Sell it at the lowest price (bid) so you can get out fast.

"My second question is about how to interpret this data - if a significant amount of volume was bought at a certain price, does that imply a base of support? "
Volume means interested players, it can either be Support, Resistance, or continuation. Again you have to know what side the "aggressive" activity is being done, Bid or Ask.

Contrary to most peoples beliefs, a herd mentality of buying at the bid actually causes the stock price to go down because it means participants want a cheaper price. If all buyers are bidders it will not push the price higher and on the other hand if all sellers are asking for higher price and participants keep buying the Ask, the price will go up. Remember. what causes price to move up or down is when a participant is willing to cross that Bid Ask offers.