1) Use set %password $$?*="Password"
This will display the password you enter as ******* and store the actual password that you enter in %password

2) Open your mIRC Scripts Editor, then click File, Font...

3) While I know this can be done, as I've seen scripts that do it, I'm not aware as to how. Sorry.

4) To restore the colours to default you can use this:
Code:
alias color.restore {
if (!$1) {
var %a = 15
while (%a) { color -r %a | dec %a }
else {
var %a = $0
while (%a) { color -r $gettok($1-,%a,32) | dec %a }
}
}

Usage: To restore all colors use /color.restore
To restore a specific color use /color.restore <color#>
Multiple colors can be specified

Note this code is untested.

5) You're missing a )
Code:
 if (!$istok(%channels,$chan,44)) {


Please note that $chan returns $null if used in a non channel event or an alias