Is there any Outlook for Android? If not, should I use an IMAP or POP3 client for Android instead? Which one do you recommend?
You don't mention which phone or Android version you're using. On my Motorola Droid (Android 2.2) the built-in E-mail application allows me to connect to my employers Exchange server. When I created the account, I had three options for connecting: POP3, IMAP, and Exchange.
There are other e-mail clients out there that may also connect to Exchange.
You could try K9 Mail. I use it for non-Exchange accounts and it works great, so I know it's a great email app in general. I believe it has the ability to connect to Exchange servers, too, so...there you go!