[CentOS] LVM & Softraid & expansion

I've been reading the RHEL 5 manual/guide linked from centos, and the idea of LVM with expandable partitions seems like a great idea (yes duh why else would it exist if not?). Although the documentation shows a screenshot of how the final setup would look like with LVM & RAID together, it doesn't actually gives the step.

1. Am I correct in thinking it should be done in this way - setup Softraid - setup LVM on the raid partitions

Secondly, LVM allows expansion of the LVM group when we add a new drive. But with softraid, how will this happen? Searching around does not turn up any guide on this. Am I correct in thinking I must always add new drives in pairs (for Raid 1), create a new softraid partition then assign this new partition to the LVM group?

Thanks!