Get a better scale this general model of scale will do the trick and cost anywhere for 12-30 $ depending on where in the world you buy it from
http://www.ebay.com/itm/0-001g-20g-..._Equipment2&hash=item2a115404ad#ht_2860wt_952
once you have the scale take small pieces of paper fold them in half twice so there is a general middle are for the powder to sit.
Weigh out 10mg on your scale remove the weighing pan with the powder and dump onto the piece of paper (make sure there is no breeze).
Do this for about 10-20 10mg amounts.
Get something small and circular to hold the cap in (I prefer silicone ear plugs for gauged ears) however anything hollow and circular that will hold the pill upright will work.
Take an envelope and cut off the very tip of it so it is triangular and then cut a small hole at the bottom of that to make a ghetto paper funnel.
Place capsule in circular capsule holder, place paper funnel in mouth of capsule, pour paper with powder into capsule and put top of cap on.
This may seem a bit complicated but there is no easy way to cap them up!
As for the filler material it is only a good idea if there is a potential for people to try and snort them because potency typically increases in that ROA.
If you are simply capping these up for personal use just empty the preweighed amount into your capsule and your golden.
Have you looked into liquid dosing as I think it might be easier for not having a precision scale.