First, if you had read a little more carefully, a combination of
1) less redundant replies and
2) more clients means more routes and ___therefore more hosts within a certain ___radius,

means little or no difference in the number of hosts received if the TTL is lowered.

Second, an algoritm that searches the users' directories(folders if you prefer) for certain file types (perhaps .mp3, you know that plenty of people use gnutella for it), and adding them automatically would be pretty invasive, but if that is what is needed, then perhaps on install, it could be an option to "Scan your computer for files to share". Even this is a little borderline, but so has the whole discussion ;/