First off, just resize your video to anything less than 25%, that way you can create a border around your clips (anything that isn't video will be black). So reduce each of them by say 23%, then postition each in seperate corners. Alternatively, resize to 25%, put locate your the outer edges of your clips outside the frame - that way you can create the border, or "cross" in the middle.
To do the logo, first create a transarent image of said logo. The image should be the same framesize as your video, with the logo positioned in the exact position you want it on screen. Note: allow for the fact that the visible area on a TV is less than on a monitor
. Now, import the image onto a superimpose layer, and hey presto one watermark!