InDesign and PageMaker are completely different products and they don't interact. I've never heard of InDesign messing up a PageMaker (or QuarkXPress, or any other program) installation.
Of course, it's always best to have a full backup of your hard drive, just in case something goes wrong somewhere. You never know when cosmic rays will hit or something. 
When it comes to training, I'd encourage you to check out the many blog posts, including this one on Lots of Free InDesign Video Training and the whole Beginner's Corner category on this site.
This article was last modified on December 31, 2009
This article was first published on
Commenting is easier and faster when you're logged in!
Recommended for you
How to Insert a Schwa (or other phonetic) Character in InDesign
How to find special little-used characters when working in InDesign
Five Favorite Design and Marketing Resources
A taste of the resources you’ll discover in Theresa Jackson’s upcoming session a...
A Script for Better Rounded Corners in Illustrator
Free script makes it easy to improve the look of rounded corners in Adobe Illust...