understanding how to set values when using all 8 bits from one address plus the next 2 of the next address
I've never used MSRDS and clicking on "Learn" on the linked site returns "No results" no matter what I do. You also haven't provided any code. So the following is a complete guess.

From what I can tell, you are trying to communicate with a device via I2C and the address you are trying to write to is 10-bits long. You are attempting to do this as:

[Address][Data][Address][Data]


Take a look at the section on 10-bit addressing on the bottom of the I2C Specification.


  10-bit addressing can be used together with 7-bit addressing since a
  special 7-bit address (1111 0XX) is used to signal 10-bit I2C address.
  When a master wants to address a slave device using 10-bit addressing,
  it generates a start condition, then it sends 5 bits signaling 10-bit
  addressing (1111 0), followed by the first two bits of the I2C address
  and then the standard read/write bit.





  If the master will write data to the slave device it must send the
  remaining 8 bits of slave address as the second byte.
  
  If the master will read data from the slave device it must send the
  complete 10-bit address (two bytes) as for writing, then a repeated
  start is sent followed by the first address byte with read/write bit
  set to high to signal reading. After this procedure the data can be
  read from the slave device.




I don't know how to get MSRDS to signal 10-bit addressing. But you need to do that and then do:

[Address][Address][Data][Data]