First of all, as I mentioned above, I personally think it's crazy to use POP instead of IMAP, because POP doesn't synchronize between Outlook-based PCs and Android devices. Yahoo Mail didn't used to offer IMAP (which is why I switched from Yahoo Mail to Gmail). But I just checked, and now,
Yahoo Mail does offer IMAP. I just now added my old, free Yahoo Mail account into Outlook as an IMAP account. There's a thread about how to do so
here. I did the following in Outlook.
Create a new acccount (and select IMAP as the account type).
Incoming mail server: imap.mail.yahoo.com
Outgoing mail server: smtp.mail.yahoo.com
Incoming server port: 993, SSL
Outgoing server port: 465, SSL
Some people claim that you have to use an Outlook add-in for Yahoo IMAP mail, like
Yahoo IMAP Connector. But I didn't need it.
Here are the settings for setting up an Android device for Yahoo IMAP mail. (No app is required.)
As I mentioned above, I think that the best way to synchronize Outlook contacts and calendar with Android devices is to simply add a free Hotmail account to Outlook and the Android device. All contacts and calendar will automatically be synchronized over any Internet connection, like 3G or Wifi. You don't even have to use Hotmail for email or for calendar, if you don't want to. You can just use the Hotmail account as a syncing repository for Outlook contacts. Whatever contacts you create or edit on Outlook will automatically appear on your phone and vice versa. It's awesome.
Click here to see more details about that solution.
Personally, I use Hotmail to sync contacts and calendar with Outlook, but I use Gmail (IMAP) for mail. My emails, calendar, and contacts are perfectly, automatically synchronized (for free with no 3rd party software or apps, and no user intervention) between my Outlook-based desktop PC, my Outlook-based laptop PC, and my Android phone.