Upgrading to 7.2

I have a couple wuick questions about upgrading to 7.2.

First, are there noticable performance improvements with 7.2? I am
currently using 7.1.2 and it is having a real hard time with large
tables(about 10million records), queries take forever(even simple ones
that are index scans)?

Second, when compiling with gcc, what level of optimization is safe to
use? I know that some code when it is compiler optimized can break
really badly.

Third, 7.2 will allow for the creation of fuinctional indexes right? In
my current version, it refuses to create them saying that it cannot
create index on max(int4);

And last of all, is 7.2 just a drop in replacement, or is this going to
ba a painful process?

--
Chris Field
Affinity Solutions Inc.