What do all these sendmail.mc options mean?

[Jim Johnson]

The README file says to add these lines to the sendmail.mc file:
INPUT_MAIL_FILTER(`spamassassin', `S=local:/var/run/sendmail/spamass.sock,
F=, T=C:15m;S:4m;R:4m;E:10m')dnl
define(`confMILTER_MACROS_CONNECT',`b, j, _, {daemon_name}, {if_name},
{if_addr}')dnl

However I've found that everything seems to work fine for me if I only use
the first INPUT_MAIL_FILTER line.  So my questions are:
1.  What does the INPUT_MAIL_FILTER line do, and what are all those crazy
options like "C:14m"?
2.  What does the confMILTER_MACROS_CONNECT line do?
3.  Why should or shouldn't I use the confMILTER_MACROS_CONNECT line?

TIA,
Jim