"only on demand"
You can always say..... "finish the requirements" "do what is asked of you" "do what is needed to be done" One of those should work for you
you've got is another way to say you have.
What is another way to say "address my concerns"? Another way to say "address my concerns" is to say "attend to my issues" or "look into my worries".
et cetera is another way to say and so on
If something is unnecessary, it is unneeded. Another way to say that would be redundant, which means that there is already something else doing what is needed. You could say that expendable or dispensable. You might even say it is beside the point or uncalled-for. Another way of saying this would be to say unwanted.
Another way to say 'events' is 'functions'
Verbose is another way to say big words.
Another way to say horizontal is flat, even, or level.
You could say first come gets first choice or you could say the first in is the first served. You could also use early bird gets the worm.
another way to say only is but what's more ,you will find or as well as.
Another way to say "back and forth" is "to and fro."
another way to say bone