Boris,
i think your rockwool is different with ours in asia. For those rockwool made in malaysia, the ph is ard 6-7. Yes you are right with the fine particular that cos skin irritation, that is because the fine strain of wool poking on your skin, so gloves are a must. Also after handling the wool, use strong detergent to wash also help. As for me, i use masking tape to paste on the part that is irritate then peal it off, it does help
Also, rockwool absorb water very fast if you buy those low density type, i would suggest your to buy 1inch 2pound type.
Yes David, just use a paper cutter to cut it to size.
