IPFS nodes generally cache data that has been accessed recently, so if your website is the most accessed content on IPFS you can host it for free just by sharing it once and users will have relatively quick access to it because nodes directly connected to them will probably have a cached copy already. If requests are rare, expect to host it yourself or pay a pinning service, and expect higher latency as users will be requesting content hosted multiple hops away. You should care whether the tech is butterflies or turtles, because you can't compare butterflies and turtles -- or you can, but the comparison breaks down when you ask which will get to an undefined point x quicker. If x is in the air, butterflies; if x is in the water, turtles.

Yes, definitely. I mean, you certainly get better bandwidth and latency depending on popularity and geographic diversity of seeders, and there are even youtube-alternative websites that host videos on IPFS. But for something like browsing from one page to the next, where the payload is small and you want <200ms latency, I think just the DHT lookup might already put you above that budget. I'm guessing though, haven't made any measurements.

Eternum is now using IPFS Cluster and should be greatly improved (I just pushed a bunch of bugfixes and significant improvements). Thanks for the tip!