You type in the full name in both cases with the variation in one of them. For example if this Maria is named Maria Ann Smith but also you find it listed somewhere as Mary Jane Smith then make one your preferred name and the other your alternative. I usually choose the perferred name if I feel my source is better than where I found a different name. Where it says "given name" I type in both a first and middle name if that is what you are asking.
Yes there is indeed. Go to "edit this person" on your person and on the right of the name is a box that says "more options". Cliick on that for alternative names then add your alternative name and decide which name you want to be preferrable, Maria or Mary and check that. You can even add more than one. Also, if you have alternative dates for birth, marriages or whatever you can also add those if you wish by clicking on options next to each. Hope that helps.