1: you wont be able to use the laptop as a monitor for your desktop. They don't have a video input, only an output to connect it to your tv or monitor.
2: the 8350 does well in rendering and will outperform the i5 in a multithreaded rendering app such as cinebench,
3: to reach the thru speed of your renders you would need at least 1 more harddrive , one source and one destinations, to avoid having a single hard drive trying to read and write at the same time. Optimal setups often ask for 4 drives, one OS, one scratch, one sopurce, and one destination. See your softwares support forums for suggested builds.
well, i said, i may render, dont need to be a pro