Determining Default Values Automatically

I am building code to look into the database and create "CRUD" stored procedure scripts automatically for each table.
I am in the finishing stages as my procedures take into consideration all necessary parameters and keys wheter they are natural or identity. It also takes into consideration User Defined Types.

I am working on the section which defines the parameters and their default values. ie.
CREATE PROCEDURE [dbo].[TransactionHistoryInsertOne]
(
@ProductID Int = 0,
@ReferenceOrderID Int = 0,
@ReferenceOrderLineID Int = 0,
@TransactionDate DateTime = '1/1/1900', <-- Possibly arbitrary
@TransactionType nchar(1) = '?' <---- How to get this.
@Quantity Int = 0,
@ActualCost Money = 0,
@ModifiedDate DateTime = '1/1/1900'
)
AS...

I have three problems remaining.
1. Using the AdventureWorks database as a data model, I run into the TransactionType field in the TransactionHistory table, a non-nullable nchar(1). How do I determine and use any default values that may be defined for this object?
2. Do UDTs have default values already defined?
3. How do I make sure I am not arbitrarily setting the default values?

Here i my select statement into the system tables:

SELECT C.*, T.name as xtypename, U.name as xutypename, S.*, so.*
FROM syscolumns C

left join systypes T on (C.xtype = T.xtype) and (T.xtype = T.xusertype)
left join systypes U on C.xusertype = U.xusertype
left join sys.all_columns S on (C.id = S.object_id) and (C.name = S.name)
left join sysobjects so on S.default_object_id = so.id
WHERE (C.id = [TableId])";


Thanks for any help