Thanks for the replies, everybody!
SuperSoaper, I was wondering, too, if the bag would eventually break down with repeated heatings. I like your idea of portioning it off into containers and putting them in the fridge, especially if the palm oil will stay well-mixed as a chilled solid and I can just scoop what I need. That way, I don't have to put an exact, pre-planned amount into the container.
ArmourSoap, congrats on your first batch! It's good to know that it's not as complicated as it can seem sometimes. I don't know if you can tell, but I tend to overthink details and get myself all wrapped around the axle. (I know you're collecting idioms, SuperSoaper, so that one was for you - enjoy.) My supplies probably won't get to me before the middle of next week, and I probably won't have the chance to soap before the week after that, but when I do I'll post the results, good or bad!
And I agree with everyone on the infrared thermometer - I love mine. I got it at Lowe's for $30-something. It is definitely worth the investment.
Thanks again, everyone! (And you're right, SuperSoaper, sometimes I do have to remind myself that I am supposed to be having fun!

)