ISO's images for Red Hat's Advanced Server edition will not be available for download. You can download all the components to "re-create" it. You can read about it here. CNet did an article about it in January.
The "professional" version is essentially the standard version. Red Hat just includes more cd's in the boxed set when you buy "Pro" instead of standard. Most of the applications included on the extra cd's are software from other companies. Some of the applications you can download separately. You can read a comparsion of what is included in "Pro" vs. "standard" here.
Red Hat 7.3 should be out within the next couple of weeks. ;D There is a rumor of it being out on May 6th. Read the Red Hat 7.3 thread.