How do I know exactly when companies are paying out their dividend and how much? Is there a good source to look it up and compare companies?
I second the Yahoo! Finance key stats suggestion, but I like Morningstar even better: http://quote.morningstar.com/stock/s.aspx?t=roic
They show projected yield, based on the most recent dividend; the declared and ex-dividend dates, and the declared amount; and a table of the last handful of dividend payments.
Back to Yahoo, if you want to see the whole dividend history, select Historical Prices, and from there, select Dividends Only. http://finance.yahoo.com/q/hp?s=ROIC&a=10&b=3&c=2009&d=00&e=4&f=2012&g=v
You can use Yahoo! Finance to pull this information in my use. It is listed under Key Statistics -> Dividends & Splits.
For example here is Exxon Mobile (XOM): Dividend Payout Information
I have 3 favorite sites that I use.
http://www.nasdaq.com/symbol/mcd/dividend-history - lists the entire history of dividends and what dates they were paid so you can predict when future dividends will be paid.
http://www.dividend.com/dividend-stocks/services/restaurants/mcd-mcdonalds/ - this site lists key stats like dividend yield, and number of years dividend has increased. If the next dividend is announced, it shows the number of days until the ex-dividend date, the next ex-div and payment date and amount.
If you just want to research good dividend stocks to get into, I would highly recommend the site seekingalpha.com. Spend some time reading the articles on that site under the dividends section. Make sure you read the comments on each article to make sure the author is not way off base.
Finally, my favorite tool for researching good dividend stocks is the CCC Lists produced by Seeking Alpha's David Fish. It is a giant spreadsheet of stocks that have been increasing dividends every year for 5+, 10+, or 25+ years. The link to that spreadsheet is here: http://dripinvesting.org/tools/tools.asp under "U.S. Dividend Champions".
Yahoo Finance is definitely a good one, and its ultimately the source of the data that a lot of other places use (like the iOS Stocks app), because of their famous API.
Another good dividend website is Dividata.com. It's a fairly simple website, free to use, which provides tons of dividend-specific info, including the highest-yield stocks, the upcoming ex-div dates, and the highest-rated stocks based on their 3-metric rating system. It's a great place to find new stocks to investigate, although you obviously don't want to stop there. It also shows dividend payment histories and "years paying," so you can quickly get an idea of which stocks are long-established and which may just be flashes in the pan.
Lastly, I've got a couple of iOS apps that really help me with dividend investing: Compounder is a single-stock compound interest calculator, which automatically looks up a stock's info and calculates a simulated return for a given number of years, and Dividender allows you to input your entire portfolio and then calculates its growth over time as a whole.
The former is great for researching potential stocks, running scenarios, and deciding how much to invest, while the latter is great for tracking your portfolio and making plans regarding your investments overall.