Re: What happens to forecasts and actuals if resource is moved from one pool to another
re: #1, The manager of the old pool should zero out any commitment as of the resource's transfer date, then forward the resultant outstanding demand to the new pool where that manager would make the commitments.
In practice, we have developed SQL scripts to do this process in order to support mass migrations triggered by large organization changes. But it's still a semi-manual process, in that the scripts need to be tailored each time depending on different factors.
re: #2 Can you elaborate on your requirement to "report on utilization"? The Analyze Assignment Load portlet will allow you to select a parent level pool and will give you the roll-up picture if you check the "Include children resource pools" checkbox in the portlet's preferences.