Small fractures can result
Small fractures can result from stress from improper annealing, or from incompatible glass. If you’re positive that the glass you used was compatible, then it’s likely that the fractures are from other stress. You could refire these or incorporate them into other pieces (with compatible glass) to create something new; but I would definitely save this for your new glass kiln. I’ve no experience with microwave kilns, but I don’t trust them;)
The haze is most likely devitrification (though it can occur from gases released from binders in thinfire, if you used shelf paper). Devit can happen if you don’t clean your piece thoroughly, or if the piece is held too long in the devit range (1300-1450ish, I’m sure someone will comment with the exact range for you ). You can fire it again with a cap of clear powder or glass to at least 1425 and this should get rid of your haze. I’ve read that certain oversprays can be applied and fired to fix the problem as well. Don’t know that the Borax water solution will fix the problem, or if it only prevents the problem. If you have access to a sandblaster, you could sandblast the haze off and then firepolish. I’m assuming a rock tumbler with silica carbide in it would also tumble the haze off, so that you could fire polish the piece, as well.
Hope this helps a little:)