Lets not get carried away, the neighbour thing was a bit cold, but I think it's one of those things where he doesnt think about the consequences, you can see and hear how relieved he is when she calls him and tells him everything's fine.
The bomb in the nursing home, he probably rigged it to blow up only one room, you can see that it only blows up the room, so a small explosion.
"Who never actually did anything to him'?! Seriously?! Are we forgetting here that at the end of Season 3, Gus was planning on killing BOTH Jesse and Walt, yep, that's right, so even though Gus was pretty cool with Jesse since Walt was out of the lab, he could have found some day another cook and get rid of Jesse.
For the kid, Walt did what he had to do to get Jesse on his side, and he probably knew that the poison wouldnt kill Brock.
Once again, I don't consider him as a monster, he simply went to extremes. Imagine yourself being in such a situation. I would save my ass with any way possible, and we can see he's limiting the casualties, he planned it really well. Everything he did, he did for good reasons.