Hello, Snickersnake!
Welcome to Apple Support Communities! From what I'm reading in your post, you're having some trouble creating Contacts from a list of email addresses that you received in an email. I wouldn't be able to memorize them all to type them in Contacts, either, so I know where you're coming from wanting an easier way! I'm happy to help in whatever way I can.
Without knowing for sure what version of iOS you have on your iPad, I'm hoping the testing I've personally done will be helpful (Your signature here says iOS 8.1.2). I have iOS 9.3.3 on my iPad, and iOS 10.0.1 on my iPhone, and it worked the same for me on both. I sent myself a list of email addresses. When I opened up the email and tapped on one of the addresses, it did exactly as you described: It opened a new email message, with that address in the "To:" field. However, when I pressed on the email address (as in, tapped and held it instead of lifting my finger right away), I got the options to either add the address to Contacts or copy the email address. Either way I tried (create a Contact or Copy) worked for me, on both my iPad and my iPhone. The difference between tapping and pressing is subtle, but it makes all the difference in getting the right menu to pop up.
If you're interested in updating the iOS version on your iPad (in case this isn't working for you), the following documents will help you back up your device, and update the iOS software:
How to back up your iPhone, iPad, and iPod touch
Update the iOS software on your iPhone, iPad, or iPod touch
Have a great rest of your week!