I'm starting a new system form a retail chain and I could use a webservices architecture to make all points online with the head
office.

I have some doubts with the architecture details but I can't find good documentation about that (the .Net have many different ways
to make systems like that). I read the Microsoft Patters but I have still some question in mind.

For example, a major question, in this system I will have stock, sales, bills and so on, in other words, if I make a single
webservice for each functionallity, I will take hundreds of that. I could make a 'proxy like' webservice, passing a id for each
function and a object for the parameters taking just one webservice. What's the pros and cons of thats architectures? There's others
options?