The real goal is not necessarily to have a mic button, but to get to the Samsung keyboard settings (or other keyboards if that's what you are using). If you tap in your text message to bring up your keyboard (it can be ANY text box, it just needs to bring up the keyboard), you will see a keyboard icon on the top left of your phone in the notification drop-down. Swipe down to open the notification area and tap on the "Choose input method". Select "Set up input methods" and tap the gear next to the keyboard. You are now in the settings area that some people pointed out can be accessed by tapping and holding on the microphone button on the keyboard.
As it was pointed out earlier in this thread, the way to turn on Predictive Text is from the keyboard settings --> select Predictive Text and turn it ON. Once it's on, you will start to see word suggestions based on what you type, as well as the Check mark pointed out in the above screenshot There are two settings under the Predictive Text menu as well: 1) Live Word Update (will download new and popular words each week via a data connection), and 2) Personalized Data. If Personalized Data is OFF, then you will still see word suggestions and can tap the check mark to use a new word instead of having it auto-correct. Just testing it right now, it is saving my new word until I tap outside the text area and the keyboard minimizes, although the this does not happen every time, sometimes it doesn't save it at all. Turning Personalized Data ON will let you start building your own dictionary. When it is ON, tapping the check box for a new word will let you use that word instead of auto-correcting AND it will save that word so you can use it later, even through changing apps or minimizing the keyboard.
If you accidentally save a word you don't want, you can tap and hold the word in the predictive text box (next to the check mark) and it will give you the option to remove that word from Learned Words. This is especially helpful because it's easy to save words you don't want due to the fact that punctuation saves words rather than auto-correcting. With personalized data ON, when typing a new word, it will be auto-saved, if you put any punctuation after it (not including a space or double-space to make a period). If I type "Cheezy" and hit space, it corrects to "Cheesy". If I hit the check mark instead, it saves "Cheezy" and I can use it later. If I type "Cheezy" and hit "," (comma) it keeps the text as "Cheezy, " and saves "Cheezy" in personal data.
If you want to remove ALL learned words, you do that in the Keyboard Settings --> Predictive Text --> Clear Personal Data. I have not found a way to view all the learned words as a list in order to delete only the ones you wish to remove, the only way seems to be to start typing them in and the long tap the prediction to remove that single word. Unfortunately you have to start typing in the word incorrectly, as that is how it was saved to begin with.
Hope that helps answer everyone's questions, I learned a bunch of new stuff while researching this myself, so thanks to those who contributed as well.