First, to answer someone's question, no, you'll not get a lower rating if the match has not begun and it expired.
Second, the info when -receiving- challenges will be added soon.
Third, not answering challenge will not be "the new way to beat the system" as it is really not useful to be in a game just to
"not answer challenges" (and you cannot send a challenge if you haven't answered a waiting one).
And last but not least, as already said, in ELO
, if someone let the game timeout, he will be -punish- at the end of the day
(severly). (and the ratio of "timed out" games in elo
vs "correct" games in quite fine)
You have to understand that it is NOT possible to avoid all the problems if some people just don't want to play fair.
For example, some people dont "let the game timeout" as a strategy but simply quit because they don't like to lose, over time
they will become orange, then red, and nobody will want to play with them.. maybe they will learn
With over 600 players connected at time, I'm sure you'll be able to find the right peoples.