you should clean the spindle. i usually use emery cloth.

do yourself a favor and buy a cheap bearing packer so you dont have to pack the grease in by hand. you'll spend about as much getting your hands clean otherwise.
also always replace the bearing race when you replace a bearing.

i stand by my statement on not turning drums and rotors which have no problems, and so do the vehicle manufacturers.
it uneccessarily removes metal, and often introduces excess runout on rotors (unless turned 'on car'), or a less than straight condition on drums, especially if using lathe adapters which have been thru hell and highwater. as most brakeshops have.
although turning new drums and rotors which are pressed onto the hub is recommended (on car only for rotors), new drum and rotor turning is otherwise uneccessary, and in my opinion, undesirable, and is not reccommended by quality part manufacturers.