Where is MVC Pattern in the Agile Stack?

I developed a Java web application for the validation and the exchange of orders with a CRM Solution, but that's not important.

The important thing is I tried to follow the principles of good programming, so Agile Development, trying to think with different "hats" on the various stages of the development. After everything I decided to write a document for my own, trying to understand what I did, and if I could've done it better. I tried to separate the themes regarding analysis and design, but I can't really understand how should I "define" some of the steps I made.

For example, starting from the beginning, reading lot of documents I arrived to understand the conceptual classes for the domain model, and thene I draw my UML diagram with the interactions, and everything has gone fine.

The next step was to draw the interactions between the conceptual classes for some of the use cases, trying to define responsibilities for each of the classes. Until now we're still talking of analysis right?

The next step, maybe to "big", was to define the web pattern to use, and I decided to work with MVC pattern. The problem is now, as all of the conceptual classes become beans, and we build a huge "framework" of classes on the top... Controller, Services, Dao, Model business... Where should we place the choice of the MVC Pattern? Is it analysis? Is it already design? I would go for the second, but it makes me thing my analisys step was way too short and I forgot something in the middle.

N-th but last question: when shoud classes that I never mentioned in the analysis stage come into play? For my example, a Validator class that works to clean my orders and that was obviously not included in my domain model be exposed? At what level of my design stage?

Thanks in advance.