1) There are no stocks I think anyone should buy for the long haul. You need to review the quarterly earnings statements every quarter for signs of trouble and track the valuation metrics of the market (which are low and good now).
2) I manually re-invest my dividends most of the time at prices that meet my buy price criteria. I'm always stunned at how even a good stock will sell off on what I regard short term issues and then I sneak in.
NLY is the perfect trading stock and a stock you need to watch like a hawk. Pull up a 1-yr chart of NLY*. Ex-dividend EVE is the #1 time to sell NLY. Ex-dividend day is the #2 day to sell. You then sit back, relax and wait for a good entry price which I think will be $15 - $15.50 this quarter.
*NLY typically drops by the about amount of the dividend on the open on ex-dividend day -- Wall Street gives the dividend and then takes it away from the price. Then NLY starts a nice little decline that can last a few days to a couple of months. NLY's distribution and leverage are both declining which really reinforce this trend.