It's main focus will be on Windows 10 and it's features. You may encounter a few things about Windows 7 but they would be things that are the same as Win 10 so you shouldn't have too much to worry about.
I don't think anyone publishes books for the MTA Exams, however if you go the exam page (below) and expand the areas the exam covers, they do show some prep areas and provide links on some of the topics.
https://www.microsoft.com/en-us/learning/exam-98-349.aspx
Hope this helps.