Hello. First of all: thank you for the great job. I revived an old 300 Mhz Clamshell iBook which can now run an up-to-date version of a firefox web browser– slowly but surely

My very first question is as follows: I installed Mintppc 9 because I assumed it would be faster on such an old machine, besides it being more stable and complete. I searched the forums through and through trying to find out wheter this was actually the case, or if Mintppc 11 would actually perform equally or even better. Or is it maybe a question of RAM (the iBook has something about 500 MB RAM).
Second question- now I presume this was answered but I couldn't find a satisfying answer: is it possible to upgrade a system from 9 to 11 like I would whith Ubuntu or OS X, which means just by playing the upgrade over the old system to find a sparkling new system in the end?