Not sure what you are asking. Are you refering to storing data on the client, like in a cookie, which is then used to fill out the form?
QuickReport works as well. It is a bit troublesome in ISAPI mode though. It is better to separate the reporting out into a background service that the web interface calls.
None. You can only use the components supplied with UniGUI. There are a couple of example extensions made by users, which you can download in one of the other subforums, but no thirdparty packages. Keep in mind that this is still beta software, although it is stable and featureful as it is.
The key thing to understand is that the components are designed to use the Ext framework from Sensha for the web part. I believe that the goal is to wrap as many Ext controls as possible in UniGUI itself, leaving little to be added by third party developers. To create a custom component, you would both have to implement the custom VCL part, as well as an web implementation from scratch. Quite a chore, I would say, and I don't see much reason to do this.
Right now the idea is to keep as high feature parity between the VCL end and the Web framework as possible, but this could possibly change. There has been some discussion about possibly losening the focus on the VCL framework, in order to speed up development of the Web part, since this is the part that most people actually need. The VCL part of Unigui primarily serves as a way to design the Web layout of the forms. The people that actually plan to deploy both a VCL and Web version of their applications seem to be not that many compared to how many that only needs the Web framework.
I should let Farshad answer that one.