It is a bit tricky to get the hand warmers in, but generally, I put the liners on, pick up one glove and slide the warmer in, while it's off my hand. I kind of hold the glove vertically and drop it in, so it's resting against the top of the glove. Since my outer gloves are a little bigger than usual, when I slip the glove on, I can move the warmer into place a little, but since it's on the top, not my palm, the placement isn't as critical. I do the same with the other hand.
Sometimes the warmers don't work as well, for whatever reason. Some brands work better than others. The cheap ones I have need to be activated for a longer time.
I haven't noticed any difference with my booties. I wore the warmers when I commuted, with the booties in the AM when it was often in the high 30s.