regarding the different frameworks used in Liferay. I would say for development, you should at least understand the framework at a high level. Minimally, you should know (high level again) the following: Spring, Hibernate, Ajax, and Struts. If you're creating portlets via the plugins SDK, you probably can bypass Struts or Spring MVC if you create JSP portlets instead, (which I find very simple to do).
Since Liferay is open source, there are tons of sample code you can learn from and also model your code after. It's just a matter of familiarizing yourself with the code structure and know where to look for them.
Also, read up on Service Builder both in the wiki and here in the forums. If you get the hang of that, it generally does all the Spring, Hibernate stuff for you in the backend.
I would also encourage you and your colleagues to attend a dev training to jump start things.
