1. Where are some sharepoint related community sites that provide new users with a positive experience?

2. One problem I am encountering – a co-worker and I have been creating a SharePoint list with a workflow, so that a user can submit requests that then move along an approval chain. That generally works. However, we would like to add some features to the entry's fields before the request is submitted.

One such thing we would like to do has to do with the people/group picker columns that we have defined for the list. It would be ideal if the current user's name could be filled into the form as it is initially being displayed. Of course, if the user wishes to specify someone else, that would be fine – we just would like
to fill in the default. However, it is not obvious to me how I would do this.

The second such thing we would like to do, before accepting the user's entry, is to take one of the columns and see if that value is already present in a SharePoint list we have created. If the user is requesting something that was already requested, we would prefer to not allow the duplicate request.
Is there any way to do this?

Thank you so much.