You're not giving in at all, and no there's no bad habits forming. These 'habits' chop & change in my experience, and are never long term. From the sounds of it, he needs some extra comfort right now. If he's been sick, and is teething, he obviously wants to know that mummy is around, which is a fair enough thing for a 1 yr old to want

Think you hit the nail on the head when you said he's going through a stage. No doubt he'll have many more 'stages' to go yet, with development and more teeth, and of course a new baby coming.. so I'd just try to ride each one out.

As for the new baby coming.. you'll be surprised how you work things out. I still help DS off to sleep, but we usually work it out around the bub, and it hasn't really been a problem. I've often sat and fed Kayla whilst sitting on DS's bed putting him to sleep. Just do what you have to