Standard tolerance is you measure them first, then pull them, and press the new ones to the same depth.
Axle (not axel) grease is the WORST thing you can put in there! Don't do it!
You need rheotemp 500 or get your grease from INTENSE, but you could have just gotten the right pre-greased bearings now.
If I wanted you to fail, I wouldn't be asking you these questions. All this information is already here. This is why I suggested 3 different vendors.
The rotors spin at 11,000 rpm'* MINIMUM. No other grease will withstand the friction and heat.
Get the right grease, or order pre-greased bearings.