Ah, yes there are often forum replies that's in a variation of 'read your manual!' but that is only to reduce redundancies since for those who have not read, the information that many of us offer would be the exact same thing. Please don't take offense to that. Think of it as just a filtering process to keep the forum streamlined.
With that being said, I hear from students & friends who often ask "Can someone explain what the manual is saying in plain English?" I get that. In fact, many of us here do...I think, hehehe. Many of us learns things differently and depending on prior knowledge level, one explanation may explain everything or may make things more confusing. Well, that's what this forum is for. We all try to chip in our own approach to understanding functions of Cakewalk & general recording process and hopefully in this vast pool of experience & expertise, you would find the solution to your problems and maybe come back to help others out in the future.
Now, the last 30 sec. of silence at the end, you can trim out the silent parts of the recorded clip by doing 'slip edit. (just grab the end of the clip & drag left until desired end point of your song)' Or when exporting, you can select only part of the recording that you want to export leaving out that undesired 30 sec. of silence at the end.
Good luck!