if minime iso isnt available, you can install the regular pclinuxos and remove all additional packages you dont need and you could end up with minime if you cut deep enough.
minime = base system + desktop environment
desktop environment = kde or gnome or xfce or enlightenment etc ..
regular pclinuxos = minime + additional packages
with the above 3 formulars, you can see that you can freely move from one pclinuxos derivative to another simply by adding or removing packages since they all build up from the same base system
If I pick minime, will it oblige me to start fresh with my Firefox and Thunderbird setup? (Just realized I could put those folders on a flash drive and import them rather than having to manually set them up again. After updating, of course. Right?)
you dont have to reinstall if you already have a variant of pclinuxos already installed. You can just add/remove package to transform it from one variant to another..you dont have to reinstall and you dont have to move anything around.
If you want to reinstall, you can tell the installer to reuse your existing home directory if you have it in a separate partition and the new system will use your existing profiles and you wont have to move anything first. If your home directory is shared with your root partition, then you will have to move your data some place else, install and move them back