To get the column size you can use the following sql statement.
LOAN is the table name and LOAN_TYPE_KY is the column name in that table
JOIN SysTypes ON
(SysTypes.XType = SysColumns.XType AND
SysTypes.Name = 'VARCHAR')
SysColumns.Id = OBJECT_ID('LOAN') AND
SysColumns.Name = 'LOAN_TYPE_KY'
As far as the database changes, one solutions might be to use user defined types in your tables and do the same in the SPs. That would take care of a situation where you have for example a user defined type MEDIUM_STRING VARCHAR(15) and then you decided to change it to VARCHAR(30).