How do you turn off the antiidle/"You're lagged X seconds to yourself"?

In /CONF, set apingdelay to 0

How do I get the channel name on the input line like in BitchX?

Type /set input_prompt [$C], or put that line into your .ircrc file

Does SplitFire do nick highlighting? How do I set it up?

In /CONF, set highlight_nick to your nick, or whatever other word you would like highlighted.

Why don't the translations work? It just freezes up or gives me no response...

That is entirely an altavista babelfish issue. I have no way of knowing when it's working and when it isn't. If it appears to freeze up, you can hit Ctrl-C once to cancel the connection. In my experience, translations appear to be working about 50% of the time.

What is Tab Completion? How do I use it?

Tab completion is when you type out a channel or nickname, hit the TAB key, and the word is finished for you. To use it, just type the first few characters of someone's nick in the same channel as you, and hit TAB. The script will either finish typing the nick for you, or present a list of other nicknames that match.