Good starts, but I feel Shiftweave is a bit underpriced at a mere double the cost of clothing, since clothing is very cheap. My suggestion would be to add a flat cost to the cost of the clothing...perhaps 500gp?
That's cheap enough that a character of 3rd level or so could afford it without it affecting his total wealth too much, but expensive enough that it's not routinely sold by any old traveling tailor in a horse-drawn cart. In game terms it means the shapeshifter has to deal with the drawback of clothes for a level or two, but as soon as that 500gp can be raised, they can be free of it.
A similar flat cost could apply to the satchel...allowing any 'container' item, like a backpack or belt pouch or sack, to be granted the properties of Shiftweave. A bag of holding should have it's cost increased by a percentage instead, so that more powerful bags are commensurately more expensive.
For armor, I suggest that, in addition to the nonmagic version you have here, that you allow nai-nek-chai to use armor with the "Wild" enchantment from the core rules. This armor is meant for druids, but can be easily extended to other shapeshifters without any balance issues. The benefit of Wild armor over 'nai nek chai armor' is that it 'vanishes' when in nonhuman form, but still provides its armor bonus...and that it provides protection even for animal forms that are a different size than the human form.
