iBook seems happier today. I figured out which boot settings to use to prevent the freezes; eventually I will make those settings permanent in yaboot.conf.
I also found out how upgradeable this box is even today: up to 1,25 GB RAM and SSDs up to 480 GB with the required parts available from a specialist store. The RAM upgrade will probably happen in the next few weeks; the SSDs are somewhat pricey and I'll need to think on it.
@Reinderdijkhuis Wow! It's been a while since I last read yaboot. Good memories.
@Reinderdijkhuis ok, it's just that I haven't played with a powerpc mac in a while. I suppose that it's still in use.