[COMLANSER]

I'm creating an invoice. Where can I find Formula Syntax information? Some
examples would be nice. "IF" specifically but I would prefer something
broader.
In "D1" { =(A1*C1) \# "$#,##0.00;($#,##0.00)" } works just fine but "IF" the
result is $0.00 (because A1 and C1 are empty) then I want "D1" to be empty as
well.
Also "A1" is a numeric value (no problem) but "C1" is a dollar amount. How
do I get "C1" to automatically format to "$#,##0.00" when numbers are entered
but remain blank if empty (I can't find a solution in "Developer").
Also can information in one table be picked up by a formula in a different
table of the same document if I give cell in the first table a name or does
each table have its own identity.
I can't believe information is so scarce (or hard to find) in this area. I
have spent hours looking. I could regroup on Excel but I hate to give up.
Many thanks in advance,
COMLANSER