EP6 and Web Services

I'm currently working with a client to implement a customer-facing instance of EP6 (as well as ERP, EM, and CRM) for an online shipping system. I've been investigating ESA as viable landscape and have been trying to analyze the risks and validate the amount of work involved before proceeding. The client also has a legacy system in place (Tuxedo) that will need to integrate with the overall solution.

I had read that all of SAP's BAPIs and RFCs have been ported as available Web Services as of Web AS 6.20. This translates the idea that all previous capabilities post-ESA are available now as Web Services and I should not have to worry about restricted access to backend systems if using Web Services. Is this correct? Where can I find a description of all the web services currently available within Netweaver?

Also, after analyzing business processes and functional requirements, I need to know how much work will be involved in implementation. How much of the work will involve custom development and how much of the work has already been done as a prepackaged application/integration? Are there currently any prepackaged Enterprise Services that come with Netweaver? Is there a respository? I read in another post that one is on the way and slated for this year. Any indication as to when?

Development: I recently caught Shai Agassi's presentation and saw the development through modelling of the processes in the Mendisino (sp) project. It looks to be an exciting technology and something that can cut custom development time. Is this currently available? What are your thoughts on it's maturity aspect?

If you can provide more insight, expand, or answer some of my questions...

Thanks!

Herb