Trouble converting AS1 ('Tree Garden II') to AS3

Trying to convert this amazing flash file Tree Garden II (AS1) to AS3. made by J. Tarbell.
Currently there are a few things about the AS1 script I am stumbling over and I would appreciate any help that can be given.

1) this.attachMovie(“limb”, nombre, mydepth, init)
Would this be the equivalent of:
var _limb:limb = new limb(nombre, mydepth, init);

2) var init = {_x:lx, _y:-ly, _rotation:r, core:c, d:this.d+1};
Is this an array?

3) var c = this.core(random(20)+64)/100;*
I am not sure what ‘core’ specifies? it comes up alot.

4) delete this.onEnterFrame;
Is this like removeing an event listener?

**5) Object.registerClass(“limb”, LimbClass);
**// Connect the class with the linkage ID for this movie clip
is this the AS1 equivalent of declaring the base class in the objects properties?

Thanks for any help on this. I think its such a great peice of work it would be a shame to have it fade into obscurity! If you have time check it out its a quite an interesting project. The .fla is open source.