Disk I/O Perfomace issue

Hi, There huge disk i/o and processor utilization in my SQL Server Azure instance. Disk Write is 50GB for a single day, but know it should be hardly 100mb. Data is getting inserted using c# code(which i dont have control of :-( ). Is there way to find 1. what database/tables are getting more disk write 2. What Process and SQL is used for disk write 3. Is there any optimization technique you know that we have ti put in C# 4. If there was a blocked transaction than how to find it later. since i will not be able to find it in real time as it can happen anytime of the day. Database is responding very slow because of this. Anything else you think which could be helpful for me.