What if any issues are there if I want to change the email address associated with my apple id?

The apple id currently is my email address is that different than the email associated with it?

Frequently asked questions about Apple ID (http://support.apple.com/kb/HE37?viewlocale=en_US&locale=en_US)

How do I change my Apple ID Name or personal information?

You can change your Apple ID Name at My Apple ID. Select your country and language, enter your desired changes, then click the Continue button. Changes take effect immediately. You can also use My Apple ID to change your personal information, such as your mailing address or email address. See How to change the name you use for your Apple ID if you'd like more information.

How to change the name you use for your Apple ID (http://support.apple.com/kb/HE40)

So will the purchases still be linked even though name and/or email or the apple id is changed?

So will the purchases still be linked even though name and/or email or the apple id is changed?

Yes.