Quicken 2000 Deluxe includes a User's Guide (PDF), on-line Help in interactive Apple Guide format, and Tips. Happy reading.
Options at Intuit's web site include the main support page, a Knowledge Base (search and browse on the same page), a page of urgent technical issues, and a list of Top Ten Issues.
Quicken.com, a full-fledged financial portal, offers message boards where you can post questions (registration is required to post, but not to read).
This CNET compendium of tips covers Quicken 98 and was last updated January 19, 1998.
Many more tips can be found at "Hints & Tips by Dr. M."
I have never read an aftermarket book about Quicken, so I can't recommend any. You might try Fatbrain or Amazon.
I had been using Managing Your Money since around 1989. I switched to Quicken when the Mac version of Managing Your Money ceased development. In addition, I switched from being an employee (with tax withheld) to pursuing my two businesses as a self-employed person in 1999. I use QuickBooks for part of my business now, but I still run everything through Quicken. When I was setting up Quicken to track my finances, I wasn't always able to find advice that suited my situation. It's important to set up your Quicken file correctly at the beginning so that will be able to generate the reports you'll need down the road (especially at tax time!). Here's how I set up Quicken to track multiple businesses and clients.