I think that you can ignore this message. Yes, the fact is that this is used to check for new messages (it executes periodically), thus, you can ignore this warning
Yes, it is possible to change the default emotions set. All current smiles are in smiles.png.
With regards to the sound, as I remember, I implemented it, open 'modules\andrew\fchat\js\priv_chat.js' file, and search for using of 'oIncSnd' variable in this file. It is commented on lines 621 and 622, try to uncomment it.
2 Lanay: I've recently started answering you, you should receive my help soon
Yes, why not. Most interesting ideas have chance to be included in following updates. Currently I already have few more ideas to this module and will implement several of them.