This is completely normal for any channel big or small. Normally it means that your normal viewers have watched and now the content isn't as watched. I would continue to watch the data come in and see what happens when new viewers see your content!
Depends. Analytics lets you check pretty much everything. For example, when I upload, I usually get a spike in views cause my subscribers are viewing the video, and then it steadies out to it's normal views/day.
However, also check to see if a certain video is shared. For example, I have a video that gets a ton of views randomly throughout the year due to its nature (You can probably guess which one it is if you have viewed my channel)
Lol, this has happened to me. We posted a spoof video about "clickbaity" titles, and did it ourselves to show the power of a "clickbaity" title. The views on that video spiked immensely, and is our most viewed video. But that video has died down obviously (as it has been awhile since it was posted). But if you're willing you can go on reddit/make a reddit account and post your newest video releases on correct threads, and that helps with the video traffic aswell.