Hi. Thank you for the comments.
The biggest question I had was:
> Hi. Thank you for the comments.
> The biggest question I had was:
>
>>> The phrase "which xxx to [verb]" is singular or plural?
Hard to tell, but....
> 1. Which letter to send is a difficult problem.
I think we want a gerund here....
1. Determining which letter to send is a difficult problem.
Gerunds seem to be always singular this far....
> 2. Which conditions to apply is a difficult problem.
Same here.
> 3. Which licensing conditions to apply needs to be
> determined.
3. We need to determine which licensing conditions to apply.
> 4. Which licensing conditions to deliver to the user
> needs to be determined. (I'm not sure about this one.)
Same here.
> The clause "which xxx to [verb]" is like a
> shorthand for "The question of which ...".
> Is this true?
> Where this is true, the phrase is singular.
<snip>
Guess you're right. But omitting it sounds, to me, like a shortening of
"Whichever xxx we want to [verb], that xxx is....". Though rather
unidiomatic.
Stewart.

Signature
My e-mail is valid but not my primary mailbox, aside from its being the
unfortunate victim of intensive mail-bombing at the moment. Please keep
replies on the 'group where everyone may benefit.