Newbie Question Dev Android App

Hello all,

So I have a web application sitting on a web shared hosting environment that has a SQL Server backend DB and a directory of PDF and Excel based files in it.  I have never developed a mobile app before but hoping to play around with a new one with .Net and C# if possible for the Android OS.   My questions are as follows:

#1.  Can C# with .Net 4.0 be used to develop this?  
#2.  Can my SQL Server connection string in my current web app just be used for the mobile app?
#3.  Most important question I have is all these files reside on the hosted server so in the web application the user clicks on a link and I simply go at that directory.   How will I be able to do this with a mobile application where would I need the files to reside, can they still reside on the host and how would I get at them because I assume I am installing the mobile app on the phone of course.

Thanks all.