Building a data warehouse

Question

Good Morning Buddys,
Actually I need build a data warehouse and I've some doubts:
1. OLTP I have these tables (Adventureworks):
Production.Location
LocationID int primary key 
Name nvarchar(50)
CostRate smallmoney
Availability decimal(8,2)
ModifiedDate datetime
LocationFK int -- example
Production.ProductCategory
ProductCategoryID int primary key
Name nvarchar(50)
rowguid uniqueidentifier
ModifiedDate datetime
ProductCategoryFK int -- example
Production.ProductModel
ProductModelID int primary key
Name nvarchar(50)
CatalogDescription xml
Instructions xml
rowguid uniqueidentifier
ModifiedDate datetime
ProductModelFK int -- example
When I transfer to Staging is necessary I have foreign key columns? I mean with varchar, not int (foreign key) for example:
STAGING_Production.Location
LocationID varchar(20)
Name nvarchar(50)
CostRate varchar(20)
Availability varchar(20)
ModifiedDate varchar(20)
LocationFK varchar(20) - it's correct? 
STAGING_Production.ProductCategory
ProductCategoryID varchar(20)
Name nvarchar(50)
rowguid varchar(20)
ModifiedDate varchar(20)
ProductCategoryFK varchar(20) - it's correct?
I've no idea if is necessary foreign key columns transfer to staging but with another data type...
some one can help me please?

Answer 1

Ok ok
following:
1. OLTP I have these tables (Adventureworks):
Production.Location
LocationID int primary key 
Name nvarchar(50)
CostRate smallmoney
Availability decimal(8,2)
ModifiedDate datetime
Production.ProductCategory
ProductCategoryID int primary key
Name nvarchar(50)
rowguid uniqueidentifier
ModifiedDate datetime
LocationFK int - example
Production.ProductModel
ProductModelID int primary key
Name nvarchar(50)
CatalogDescription xml
Instructions xml
rowguid uniqueidentifier
ModifiedDate datetime
ProductCategoryIDFK int -- example
When I transfer to Staging is necessary I have foreign key columns? I mean with varchar, not int (foreign key) for example:
STAGING_Production.Location
LocationID varchar(20)
Name nvarchar(50)
CostRate varchar(20)
Availability varchar(20)
ModifiedDate varchar(20)
STAGING_Production.ProductCategory
ProductCategoryID varchar(20)
Name nvarchar(50)
rowguid varchar(20)
ModifiedDate varchar(20)
LocationFK varchar(20) data type? - example
Production.ProductModel
ProductModelID int primary key
Name nvarchar(50)
CatalogDescription varchar(20)
Instructions varchar(20)
rowguid varchar(20)
ModifiedDate varchar(20)
ProductCategoryIDFK varchar(20) -- example
What my doubt?
all columns in oltp (primary key and foreign key) exists on my olap table? i mean using data type varchar(20) - in columns : 
ProductCategoryIDFK varchar(20) 
LocationFK varchar(20) 
because i have no idea how can i load fact table without relationship...
you understood?