Oops, I missed your other questions:
Re #2) Thjat's not a supported operation. You certainly can't copy the config directory since that picks up some binary files as well as text files. In SlickEdit 2009 (v14) we have the capability to export and import options. We have not tested this cross-platform and cannot guarantee it will work. For most options, it should. SlickEdit 2008 does have the capability to export key bindings, and that should work across platforms.
Re #3) Call sales for any applicable discounts. We do offer bundles, but I don't know about upgrading from a single license to a bundle.
Re #4) I believe we have relatively good support for Xcode, though I think there is currently an issue with their latest version. I'd be interested in hearing from Mac users what their experience is with Xcode. A native version of SlickEdit for the Mac is not currently in the plan, sorry.