1) How do I avoid the "credits" when I connect to a tclTCP server?

If you avoid using "tcp login" by specifing a server command, then you
shouldn't see the credits returned.

Execute this script on a tclTCP version of wish or tcl:
source [info library]/init.tcl
proc bye {} {
    foreach s [tcp servers] {
        $s stop
    }
}

set s [tcp server -port 2323 -command "tcp eval"]
puts stderr "server is $s"
$s start
puts stderr "$s started"
set status [tcp mainloop]
puts stderr "tcp mainloop returns $status"

Then telnet localhost 2323, and you shouldn't see any greeting.

