Remove the bottom few leaves of each cutting so that you can insert the stems without having any of the leaves touch the soil...or another plant. I've never waited for a succulent cutting to callus over...so get them into a coarse medium pronto. Water them well initially.

You want the water to get to the bottom of the root ball, in sufficient quantity to really soak in. If you wait for the first few inches to dry out, then do a slow soaking, you should be fine. But, 10 minutes may not be time enough, I don't know your soil. To be safe, extending the time to 20 min. might be better. If you want to get REALLY careful about it (read anal :-)) you could then dig down next to the rootball and see how well the water spread - but I don't advise it - you would only have to put it all back and remulch.

It does not appear to be an overwatering problem; if that was the case, you would see damage at the bottom of the plant. It appears to me from the background info you provided that it was burned from your treatment. I use a dish soap/alcohol/water solution on mine with no issues, but you do want to be sure not to spray the plant before it will be exposed to sun. I find it works best to spray in the late afternoon/evening, then the plants will dry off before the sun hits them again the next day. Also don't spray so much that you have large puddles of liquid sitting on the plant. The good news is the plant isn't rotting and it will live, although as it continues to grow you may get a gap between the new growth and the leaves that you have now. At some point you can behead the plant if it looks too odd, but give it a while to recover.

The usual recommendation for watering of established woody plants in the landscape is to water heavily, about once every one to two weeks (Temperature, rainfall, and windiness dependent) and then allow to dry out significantly. Japanese yews, BTW, have a strong dislike of poor drainage. That more than anything else will spell their demise in the landscape. So hopefully, yours are not in a situation having that as an attribute. +oM