Hey, where did you get the second point from. This is wrong. First one is correct, however, let me give you some more details here:
The firewall, when translating port for NAT overload, splits the available ports into
three pools:
Low: 0-511
Mid: 512-1023
High: 1024-65535
If a packet inside you network comes into the Firewall destined for the Internet, and it
source port falls into one of those pool, the PIX will translate it to another port in
that pool. When the Firewall first starts translating addresses, it starts with the lowest port number in each pool. That means the first UDP packet sourced internally from a high port will get sent on the Internet with a new source port of 1024.
The next UDP high port translation will go out with a source port of 1025, so on and so
forth.
I hope you find the above information useful. Here's a good link for you where you can find some more details on this question:
http://www.cisco.com/en/US/tech/tk648/tk361/technologies_q_and_a_item09186a00800e523b.shtml#qa13