Persistent Systems Lead Architect/SalesForce.com Senior Developer interview questions

There were 2 rounds of phone interview 1+ hour long. Both were very technical and very difficult, with questions ranging from SFDC domain knowledge to how-to-implement use case scenarios and about integration. Visualforce, Apex classes syntax and execution related questions. I was also asked how-to implement data import of from external source that are located on a FTP server. Since I had not implemented this earlier, I was given 15 min to research and submit a solution to analyze my ability to research solutions for unique and technically difficult integration issues. Advice: prepare hard technically.