iphone 5s

To whom it may concern,

I have a couple of questions and concerns about my Apple iphone 5s. My first question and concern is that, my iphone un-downloads my apps a few at a time and I'm not sure why. Would anyone in Apple support know why this would be happening? My other question and concern is that my battery continues to die on a sufficient percentage. For instance, my battery will be on 50% and die and when I go turn it back on, it shows the charge symbol. However, I will place it on the charger to get it to cut on, then I remove it from the charger. I have always allowed my battery to get below 20% before placing it on the charger, and I do not let charge over night. So, I am unsure of why these problems seem to occur and I was wondering if anyone knew of better solutions or ways to fix these problems.