It's not totally clear what result you expect. But...
Trim video 1 in the bin by first clicking on it Under the preview window move the scrubber (red-line) to where you want the clip to begin. Click SET IN. Move it to where you want the clip to end. Click SET END. Click the ADD button and the trimmed clip will be placed on the timeline.
Do the same with the second clip. Then add a transition between them. That's about as automatic as it gets.
Alternatively, keeping in mind that higher video tracks take precedence, you might place video 1 on track one, and video 2 on track two, at :50. When play gets to that point, only the track 2 video will be seen.
If you want a fade from V1 to V2 with that layout, program a fade up at the head of video two. Click the f symbol... 
All audio channels will mix, unless you split and mute (or delete) unwanted portions. First, right-click on the video track and 
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