From client point of view it will either send a UDP message to the DHT and get a response, or send an HTTP request to a proxy server and get a response.
You will only make these requests as frequently as you make requests to DNS servers (infrequently), it doesn't do what IPFS do at all, just a censorship resistant distributed dns server.
My issue with foo.i2p is that unique readable names is untainable, people will squat and buy and sell and it is very hard to keep that decentralized.
Using ed25519 keys, makes it so the key itself is the TLD, you don't need http://
Phone numbers are not human friendly but we already know how to do good contacts UX over that.