Without a
Blackberry data plan you can do phone and SMS only.
You can use anybody's OS on your 7290 as long as that OS is listed as for your specific model. You cannot use the OS for a 7520 or a 7230. Follow the upgrade guide for updating your 7290:
How do I upgrade the OS on my BlackBerry? - BlackBerryFAQ
To change ringtones, ring volume, etc, on the Blackberry it's done from within the Profile. Go into Profiles, scroll down to the bottom and select Advanced. Then click on the Profile you want to modify to get a list of all the different notification events. Click on Phone and make sure it's not set to Mute. Choose the ringtone you want, volume, and then use the thumb wheel to access the menu and choose Save. Remember to save each individual change or they will revert to what they were previously.