Questions about building psqlODBC on Linux/Windows

Hello,

Please let me ask a few questions about building psqlODBC on Linux and
Windows.

Q1: What differences in functionality are there between the driver with
libpq and the one without libpq?  Which has richer functionality?

Q2: Do I have to specify PG_INC and PG_LIB to build the ODBC driver on
Windows with nmake even when LIBPQ=no?

Q3: When should I use the ANSI driver?  I'm not very sure even after reading
the FAQ.  Is the following understanding correct?

Unicode driver must always be used when the database encoding is UTF-8.
ANSI driver must always be used when the database encoding is not UTF-8.
Violation of above rules results in strange behavior when the character code
is greater than 128.

Regards
MauMau