In EIGRP, what are the default hello intervals for a 'slow' link (<1.544 mbps)? For fast links?

Answer 1

The default is 5 seconds for fast links like LAN or high-speed WAN links.

For slow-speed WAN it's 60 seconds.

You can typically configure these to be different though.

You'll find a good all-around description of EIGRP here: http://www.rhyshaden.com/eigrp.htm