When it comes to Thread Management you have:
The Amazing Joe Joe's.
TM (Thread Manager) Generation II - Mark Allen
Spinnerets by Steven X.
Bullets by The Great Steve Fearson.

I know that Bullets can be replaced with the good old Woolly Nylon.
I want to be able to re-spool thread managers with Good Old Sensible priced old Woolly Nylon when the spool ran out of the custom
super hyped latest and newest awesome thread.
Anyone know of a series of Thread Managers that allows you to fill it up with Woolly Nylon manually ?

Joe Joe's Is my personal choice and it is made just for that - spooling your own thread like WN, Vectra... Both the "Web Spinner" which is a physical product that I use a lot and can be purchased cheap on his site (under DIY Web Spinner Kit) There is also his newest (over a year old at this point) Super Spinner which you can make for free. He put the whole thing online for free but accepts donations. Simply go to http://magicjoint.com/forums/? and scroll down to "Products" on the left of screen.

I have no idea about the TM G2 (never seen one)

Spinnerets are a no-go. They are not "refillable"

and Bullets are a great option also. I have several but do not re-spin them (as I have had no need to as of yet)

I am so happy to know that you are using Joe Joe's web spinner Poof Daddy because I have a question about it !
Does it lock ? Can it lock after pulling a specific amount of thread ?

Yes.

I use the Web Spinner to strip my IT. Great tool.
But I make my own bullets. I was making them before they were on the market.
I bought a dowel stick. Cut it into pieces, sanded it smooth with a Dremel, wound WN thread on it, added wax and put it into a pen with the cartridge removed.
I make about 5 at a time as I need them.
You can unwind as much IT as you need and then screw the pen together and it's locked.

How long a thread do you wrap around your own custom made bullet ?

I wrap around 20-30 ft of WN thread around my bullet.
When I use it I unwind as much thread as I need and then recap the pen, which locks it .
About 2 ft for floating bill. And about 5 ft for spinning hummer card. It goes from pen, to behind ear to wax on card.

Ill thow in my vote for the Web spinner it's great. Makes stripping easy and can be refilled easily