Since you're brand-new, here's an important question: are you using Rotobrush intuitively? You can't: it'll baffle you every time.
Using YouTube Tutorials? Skip 'em and get your information from people who wrote the software, along with AE veterans with decades of experience who know all the cool tricks.... which you'll find here:
The online resources section is a good overview, and the information below it has all the details. It's a fine reference.
That red indicator merely means AE isn't playing back the frames at the proper frame rate... which is kind of erroneous, because AE can't play anything. It has to render everything. It's not an editing application, and it doesn't work like one. So you do a RAM Preview by hitting zero on numeric keypad. Here's good information on previewing in AE:
You also seem to be a bit confused about frame rates. Your camera DOES NOT shoot at 59.94 frames per second.... no, no, no. It shoots at 59.94 FIELDS per second. Since every frame contains two fields, this means your camera shoots at 29.97 frames per second. It also means that you're shooting at 1080 HD.
Finally and most importantly, you need to understand something ABSOLUTELY CRUCIAL to AE Wisdom: it's not the kind of application you use for a couple of tricks and expect things to turn out right the first time. It takes a good knowledge of the AE basics to make it do what you want. If you blow off the basics, you face countless unproductive hours of frustration.
So how do you get the basics? You go here:
If you follow the link above you'd probably stumble across what may be the best FREE training in AE Basics, compiled by Adobe's own Todd Kopriva:
Read all the glowing things Todd writes about this series of tutorials.
Well, that ought to get you started on what many people consider a journey rather than a destination: true Affer Effects Enlightenment.