suppose a portion of my IB account is long term and I want the dividends on select stocks reinvested back into the stock... can IB do that?
You really don't want to blindly reinvest dividends. There is no reason to plow them back into the same stock. When you amass enough dividends to buy some shares, put them into the best stock you can find at that moment. Forget about amassing a certain number of shares of ABC or DEF. It is psychologically pleasing but unlikely to be an optimum strategy.