does bolt number 16 at the very bottom of the fork outer actually hold some inside each fork or can it be used removed and used as a drain

yes, it holds 10,27 to it.

you'll find that it won't undo as the thing spins in side.

it needs to be locked with a special tool (which can be made with a broom stick/welded on allen) from inside the tube

Sometimes you can get lucky with an impact driver and they'll loosen off , not always though .

If you want to just drain the forks then take the top bolt off (mind the spring) then just tip it upside down & leave it for a few minutes to drain out, sometimes helps to pump the fork leg to get the last few dregs out.

ok thanks a lot will just take top off and leave upside down overnight then

Be careful when removing the top bolt !! The spring exerts quite a bit of force and the bolt/cap will spring up as it comes free . Try holding a rag over the top to catch the cap as you loosen the final thread .