It all depends what you are doing with the bot, how much traffic it has to handle and so forth.
The config file is just plain old Tcl. So when eggdrop starts, it will load the Tcl library up, and run the input throught he Tcl parser. Seeing as source is a Tcl command, Tcl will load the scripts when it comes to these lines.
There is not that much going on inside eggdrop. It just takes a little extra knowledge to understand where things come from. IE, Tcl has a base set of commands. Eggdrop provides it's owr Tcl commands, so that scripts can interact with the bot. For this, there are 2 types of Tcl command, core and module provided. Core commands like adduser and bind are a must, due tot he fact they are included in the core part of eggdrop (IE, if they are not there, other parts of eggdrop do not function). Module provided commands like channel, notes, putserv and so on, are provided by the modules they are related with. IE, you don't want the putserv command unless you want the IRC support loaded in.
At the basic level, each module provides commands, realted to the function of the module.
This is no source documentation. Keep reading the source, and you will understand it (wort of) one day. To this day, I still do not know C. I can't even manage the "Hello world" program without reading it from a book, but I can read through the eggdrop source without much problems (with exception to the socket code - Yuk).
As for making sugestions, you can subscribe to the
eggheads mailing list (the developers site). I would not make any sugestions, unless they will benefit all users, all networks and is 99% IRC related instantly. This is what Tcl is for.
What sort of information about eggdrop do you need, and we will try to supply it.