Use CAST (it's ANSI-standard), and CAST the final result as well, if you want a specific size of result:

CAST( CAST( SUM(Principal1) AS DECIMAL(5,2) ) + CAST ( SUM(BankInterest) AS DECIMAL(5,2)...

See if this gives you what you need -- it should at least be very close.  Btw, T-SQL isn't like C#, you don't need separate statements for every calc.

For that type of table definition, I'd suggest forcing all LOB columns completely out of the main table space (since SQL doesn't allow you to customize column-by-column).  That should avoid...

I'd use CROSS APPLYs to determine the lengths (this helps keeps the other code "cleaner" by pushing calcs/computations into CROSS APPLYs).  For example:

SELECT PCMRetrievalCode, LenOfSchemaId,...

I still don't understand why you need the index in string format to determine that.  It's actually easier to accurately compare the meta-data rather than a string definition (where noncritical...

SELECT string, LEFT(string, split_byte - 1) AS string1,
    SUBSTRING(string, split_byte + 1, 8000) AS string2
FROM (
  VALUES('Apple is Red and Grapes are Purple'),

I'm going to label each q so others can comment without having to repeat the full q:

A1) transaction log back up verses a full back up? 
A tran...

For that INSERT, no.  In fact, SELECT ... INTO dbo.new_table...

DECLARE @start_date date
DECLARE @end_date date
SET @start_date = DATEADD(YEAR, -1, GETDATE())
SET @end_date = GETDATE()

SELECT
  AccountNumber,
  CASE WHEN MAX(CASE WHEN row_num =...

Btw, just based on the pattern of code in your OP, it looks like you're doing a BETWEEN range on a datetime.

Put simply, DON'T do that, ever.