I created a document on iPad Pages. Wanted to view on Mac, but said I had to upgrade to Yosemite first. Is that safe?

Make a full, bootable clone of your Mavericks system before you do anything. You will not be able to reinstall it easily, unless your Mac shipped with it, or you saved a Mavericks installer. You should install Yosemite on a separate partition or hard drive, rather than installing it over Mavericks. That way you still have your Mavericks system in case you hate Yosemite or find that it causes problems. When you download the Yosemite installer, you should save a copy of it. To do this, instead of letting it run when it finishes being dowbloaded, QUIT the installer app, which is located in your Applications folder. Option-drag it to a safe location outside of your Applications folder to save it. The one in the Applications folder will delete itself after it finishes installing Yosemite.

If you don't have a separate HD for a complete backup, you should get one. Drives are cheap. An app such as Carbon Copy Cloner or SuperDuper can make a bootable clone of your system HD. This is better than a Time Machine backup and should be done regardless of whether you are using Time Machine on another drive. It will allow you to use different OS versions, and to recover much more easily from problems with your main system.

Suggestions:

1. Yes, Yosemite is "safe". Works very well on my Mac.
2. Before you consider upgrading to Yosemite, determine if any of your apps or hardware (like your printer) will be incompatible with the new OS. This will take some research online. Roaring Apps is a good place to start. http://roaringapps.com/
3. Take a look at your printer manufacturer's website and see if it says anything about Yosemite compatibility.
4. It is a good idea to keep up with OS upgrades for security purposes. That is because when a security issue is identified and corrected in a software update, it is the older OS versions that are vulnerable.
5. It is essential that you make a backup of your current system before attempting an OS upgrade. This can be done easily with an external hard drive and Time Machine, which is backup software that already comes with your Mac. External hard drives are very affordable these days. If you have a good backup, then if you have a problem with the new installation it is very simple to restore your Mac from the backup. If you don't have the backup then it can be very difficult to restore your Mac to a previous OS.
6. Another option is to make a separate partition on your hard drive and install Yosemite there, and then try it out. If you don't like it you can just erase the partition and Mavericks would still be there.

Can I go back to my old version of pages. If so, how?

The new version of Pages installs without deleting the old version; you should still have it in the iWork folder. But...... once you open or edit a document in the new version, you cannot open it in the older version. As the new version is the new default for opening documents, you would need to find an older Pages document, do a 'get info' (hit Command + i) and, in the get info window, scroll down to open with and choose the older version and choose 'open all documents'.

You should have really started your own thread as your question has nothing to do with the OP's question as it might get too confusing.