Take a couple of weeks to get familiar with these songs. The toughest part is to stay in rhythm. Be patient. Your rhythm will get better with a lot of practice.
Why learn only Song Parts instead of the whole song?
From my experience with 100s of students, it is best to learn small snippets of songs as a beginner. The main reason is because it introduces you to a broader spectrum of techniques. It also keeps beginners interested. Learning a whole entire song requires a lot of patience which most beginners don't have. As you improve, patience grows. You will know when it is time to learn a whole song.