For #9, the syntax you want makes it harder for a variable to contain a semicolon. You can do like:

Code
alias testcomment {
  echo -a $scriptline | ; this is a comment
}


Pro Tip: You can also begin a line with REM instead of a semi-colon, which is why things won't go well if you try to create an alias of that name. i.e. this will create a bracket mis-match in alt+D window which might be hard to locate:

Code
rem {
  echo -a scriptline
}