I've been enjoying mine for a couple of years now on my desktop. Great all around. Very similar to the JBL 3-series, though without the godlike constant directivity. Great bass down to ~40hz in a typical desktop setup where you have a wall behind them.
Anywhere from... let's say 3 to 10 hours? Depends on if you're familiar with basic soldering, and how fancy you go with the finish.
There are some drying steps involved so it wouldn't be 3-10
consecutive hours
At the most basic level, you could sand the MDF and spray paint it. Or throw some chalk paint on there and then give it a wax seal rub. Or at the high end you could go for true furniture quality veneer finish, or get crazy with automotive paints and 1200grit sandpaper.
The assembly video Amir linked to above should give you a good idea what you're in for. On the product page, PartsExpress also gives you a PDF manual that lists additional supplies (wood glue, etc) that you'll need.