No, and no. Each figure has a distinct shape and different rigging, so out of the box, you can't fit conforming clothing from one onto the other.

Also, don't make the mistake of confusing Stephanie with Stephanie Petite 3, these are different figures. And don't confuse the Millenium PreTeen with Laura ("Young Teen"), as, again, these are different. Stephanie and the PreTeen were part of the second generation of the millenium figures, SP3 and Laura are part of the third generation, and although they share mapping and can share morphs and maybe poses to a certain extent, that's about it.
If you are talking about the original Stephanie, she shares JPs with Victoria 2 and 1, so any clothing that you see for her will be useful. Also, if you head over to AprilSYH's website, there is a remapped version there that can take V2's textures, because out of the box, she shares just Michael 2's and Aiko's (the ORIGINAL Aiko, not Aiko3 which is the popular one).

Dynamic clothing can be easy to move between characters, because there are no JPs involved. For conforming clothing, you will have to use a separate utility, like Wardrobe Wizard or Clothes Converter, and then your results will vary.

For hair, you can use one of Netherworks' hair fitting kits (free in his site); although most hair can be repositioned by hand and parented if it is a figure, so that's easy.

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