I think everything that is happening is fine, I just want to make sure I understand.
It seems that two of the spidermen had readied actions to attack anyone that came in, and knew we were coming. Did they know exactly where we were, or just hear enough to guess that a threat was imminent?
If they know exactly where we were, why was there a surprise round? Shouldn't it have just been a regular round? Or was it because WE didn't know where the second (and third) fellows were?
If they did NOT know exactly where we were or when we were attacking, should their attacks have gone off in the surprise round? Or should those readied actions have happened in the first regular round?
EDIT: DM please also let us know if I:12 is difficult terrain.
It's strange and good that you should ask this, I was going to ask other people after the fight what they would have done.
The situation is I already have an Init rolled for the Spider Humanoids- they became aware of your approach, and probably your number and (more-or-less) location when you moved in to the webbed area, yes a fault of the map - but this is a game, not the real thing- they're spiders, you're flies- that's how it works.
Their actions were Readied only to go off when someone moved in to the chamber proper- in to combat effectively when Kali charged in (I didn't want to interrupt the charge- he did such a lot of damage).
I did give you CA to make you think it was a surprise round- note both of Kyalia's attack should have missed, but - what's 3HP amongst friends.
So, out of game mechanics, they knew you were there- they have a set defence, they waited for one of you to get close- away from his friends, they attacked.
Kali moving in to attack triggered the readies- the readied actions went off. That seems reasonable, remember some of this me wanting to make you think one thing while another thing is true.
Also consider this, what if there was another monster in this chamber that wasn't aware that you were there- do you get a surprise round then, even if you can't see the other monster?
Obviously it works the other way round too- the second to last combat you argued that Freggo should have a surprise attack...
Hope this is okay, my interpretation of the rules- seems to work fine.
I'll say it again- I sometimes want you (the players) to think one thing is true (you have a surprise round- the creature's have not spotted you or are not reacting to you), while the truth is something different.
I12 normal terrain.
Cheers Goonalan