1) I have two Templars; one I'll have to dynamite apart, the other probably would come apart with just a chisel. Neither are pinned at the waist.
2) Last week, I put together the second Templar and a Shadowcat. Neither was overly troublesome. It's been a while since I've assembled the Bushwacker...I remember a little bit of an issue getting the legs assembled to the torso, but that's about the time I learned pinning, so all went well after that.
3) What's really been helping me lately, though, is Silly Putty. It's so useful I just ordered 5 or 6 more eggs of it. O0
It's wonderful for making little columns to support the parts of the 'Mech you want to stay glued at a particular angle. I'll also use it to wedge in between arms and torsos while they dry to keep the arms from just falling flat against the torso before they dry.
It's wonderful for holding legs onto waist/torso pieces. I glue the legs/feet down, put the Silly Putty between them in a shape like a miniature Greek column, then add glue to the sockets on the waist/torso piece. I'll set the torso piece to rest on top of the column, then squish the waist down and the legs sideways into the Silly Putty until the hips meet the waist sockets, then just let go.
It'll hold that shape exactly as I want it to be until the glue dries, then I just pull the putty out from between the legs. Some inevitably separates and stays attached to the mini, but just touching it with the rest of the Silly Putty makes it come right off cleanly.