Modularity, Data and Menu Questions

Good Day to All,

I am continuing to evaluate the Outsystems environment to build software to replace our company systems and have a couple, well 3 actually, of questions that I hope someone can answer for me;

Modularity - What is the best approach for me to implement my concept?  I know its an open question so let me elaborate.  My design involves various 'Business Unit' based environments, for example; Wholesale, Shipping, Warehousing, Product Lifecycle Management etc.  Should I;

a) Create a single Outsystems application and implement the business unit environments in Outsystems modules, or
b) Create individual Outsystems applications for each business unit environment?

Data - Am I right in assuming that if I had the majority of my database tables in a specific application/module and marked them as 'public' I could reference, access and manipulate the date from other applications/modules?  The reason I ask is that I am looking to have and environment which will act as the 'Master Data Management' area to manage many of the core data, drop down etc. information.

Menus - This is probably a case of not being able to see the wood for the trees and missing the obvious but I'll be damned if I can figure this out.  Simply put I would like to have a menu item on a web page (that links to nothing) but will 'drop down' to provide sub-menu items that link to other web pages.  

On a side note I have run through the training videos and have to say they are some of the best and most to the point training videos I have ever run through - kudos Outsystems.

1) Check out the 4-layer architecture proposed by Outsystems. this will shed some light how to approach it. 

2) you can do whatever you want. see 1) for suggestion.
what I normally do is create 1-multiple data-espaces where the entities are public, only read-only.
this will force me to create wrappers around the CRUD-actions, but it does create a single-responsible espace(s)

3) hands-on experience and you will see how easy it is.

J,  thanks, I'll review the architecture links you provided.

Menus, figured it lol :)  SImple once I removed a few incorrect assumptions from my brain.