PostgreSQL index issue

Hi Fellows

I have a question regarding PostgreSQL 9.1 indexing.

I am having a table and want to create a index for a column and I want to store the data with time zone for that column. The questions are:

1. Can I create a index for a column which store time stamp with time zone. If can is there ant performance issues?

2. Also I can store the time stamp value with zone as a long integer value. If so what is the difference between the above step. Which one is better.

Many Thanks.

Roshan