Yes, it works well for video editing.
Yes, it works well for video editing.
Depends entirely on the scale and intricacy of your changes. A few basic clips tweaked for a YouTube video are fine, but professional editing usually isn't. The tools you use and their performance also play a major role.
It wouldn't be accurate to call it great, but you have the option to make changes. The encoding process could be slow if the file size is large.
It should work fine. Editing on an i3 550 is possible; the issue was mainly the rendering, which ran much longer than expected. A full render took about 10 minutes instead of the claimed 1 minute. This isn't a reliable estimate for performance or threading efficiency.
Your i5 3470 is a solid choice and can be quite affordable, helping you save money on your PC build.