The Surnames Database is also helpful with the origins of names

http://www.surnamedb.com/Surname/renfrew

The Scottish Register of Tartans shows a Renfrew tartan here

http://www.tartanregister.gov.uk/tar....aspx?ref=3498

You are right not to worry about the spelling. There are literally hundreds of variations for every name.

I think it's great that you are learning about your Scottish heritage... but be careful it can be addicting :-)