Windows 7: Outlook 2007 newbie

Yes I know it's 2010 but I just bought Outlook 2007 I needed more capabilities than Windows live could give.
First question will 2007 only import addresses in excel format, or can I import my wab.exe from OE?
Second I webmaster 4 websites and have over a thousand e-mail addresses, I have imported about 400 (already had them in Windows live mail) and put them in categories, how when I send mail can I just choose a category of names to send to instead of filtering through the 400 I have added and thousand yet to come?
Here is the real kicker, when I loaded this OS and all my backup files from XP I saved thousands of e-mails now I can't read any of them unless i use notepad or wordpad.

#1
Outlook 2007 cannot read Windows Address Book files. You'll need to open them back up in WAB and export them as a MS Exchange format.

#2

• In Outlook, go to your Contacts section.
• From the View menu, select Current View, and then By Category.
• Highlight the category you want to send email to by clicking it.
• In Outlook 2007, from the Actions menu, select Create, and then New Message to Contact. In Outlook 2000, 2002, or 2003, from the Actions menu, select New Message to Contact.

#3
From the File menu, select Import, and then select Messages, choose the software you wish to import from and click next, browse to the location of your messages then click next, choose to import the messages from All Folders, then click next. Click Finish to import your email messages.

Thank You that helped alot