Depending on network, you can obtain mode information, ban information, I-line information etc. from outside the channel by using /mode #channel <switches>
(Hint, you may need to send the command twice to get a result). This won't show you channel limits afaik, and won't show you the key if +k is set (obviously).
/names would only show you users not set invisible from outside a channel, so is probably useless in this context anyway. /list shows channel size and topic but (a) you don't want to use it, and (b) would flood you off on some networks even if filtered for a particular channelname only.
I suppose if the channel is registered there, you could always script some sockets to get the latest user count from somewhere like SearchIrc.com... but that seems horribly complicated