I don't use SMD bits for soldering SMD - I use a pair of normally closed tweezers, and a soldering iron with a 1mm tip on it. Works very well (well enough for those 80-pin 0.5mm spaced PICs).

0604 is the smallest I've done for resistors, but I tend to use 0805s instead (and 1206 if I need a bit of current).

I did buy some 4-resistor 0402s for a project, and also to see how I get on with them.