I'd recommend using a hot plate rather than hot air. That way you heat up the entire board, and when it reaches the point at which the solder has melted, use tweezers to pull off all the parts you want to salvage. Only takes a few seconds and I think it's a lot easier than hot air, especially if you want to salvage several parts. I don't even bother using flux most of the time I do this (though flux does help).
That said... getting the parts off the board is the easy part. Now you need to prep the parts so they can be resoldered. You'll need to clean the pads/leads with IPA, inspect to see which ones are in fact reusable (beware damaged/bent leads or QFN lands than have detached). Then you'll need to possibly remove excess solder on some of the QFN lands so that you have half a chance of getting good planarity when you go to reattach it to your own board. Etc., etc.
In the end, you'll likely be wishing you spent the extra money to just buy new (and guaranteed non-counterfeit) parts to save yourself the time and hassle. Just my opinion.