2) Yes, that would work fine, though it wouldn't do anything at that point, since it only sends to channels other than the one it triggers in, and if you only have 1 listed, then there isn't any "other" channels for it to send to.
3) Create a third variable, probably call it %colorList, and format it $+($chr(3),2) repeatedly but seperated by spaces (if doing it in mIRC's own editor, you can just use Ctrl + K, followed by the number). In the part where the message is sent, use $+(%chan,: <,$nick,> $gettok(%colorList,%a,32),$1-) instead of what's currently there.
Formatting it for an alias might take some extra work compared to the other 2. For example, $chan will almost likely not be available unless triggered from an event like on Text. You'd need some way of telling it what channel to check for, so possibly use $active if it runs by typing the command (assuming that is a channel, you'll want to add a check for the possibility that the active window isn't a channel, and possibly display an error message and halt the script if it isn't).
2. What I meant was like:
on 1:text:*:#originalchannel: {
var %networkList newnetwork
var %channelList #newchan1
3. yes about colorlist what if I want
blue colour --> channel1
and
red colour --> channel2
if another on text event is calling the alias is $chan available then ?
