I'm a big fan of pasturing dogs/whatever at the entrance after trying it, and have been using it since just before 0.34 came out. Thank you to whoever it was I saw post the idea. Thank you!
I checked, and one of my dwarves had a second child almost exactly 9 months after the first (both born in the fortress).
Something nobody else has mentioned is that dwarves do
not remarry (that I have seen or heard about). This means that if a mother is cranking out too many Dwarf-Child-does-what-it-pleases, knock off her spouse and she'll breed no more (assuming that for some reason you don't want to knock
her into the magma moat or under the about to be lowered drawbridge "accidentally").
As for walling themselves in, the others have posted the basics: they want to build from the W, N, E then S, in that order, and designating something else on a particular tile
unually keeps them from standing on it when building. A more reliable method, that requires more micromanagement, is to closely watch as they approach to build a particular item that will cause them to get stuck, and suspend the build job
after they have started, so the item is placed, but
before they complete it and wall themselves in. Once they have walked to safety, unsuspend the job and they will walk up to it and they (or another dwarf) will immediately get to work from whichever side they arrived at. I have been having no issues with this method, other than remembering to only enable the "dangerous" builds when i'm able to monitor their progress closely (I swear, my 6yo son is less management intensive
).