1031 Exchange Questions

[Shirley Gregory]

Hello - I own a sfh that I rent out and my tenant recently expressed some interest in buying this home and I am interested in selling it, so it's a win-win.  I have about 100k in equity in it and would like to know if I could use that money to purchase a primary residence to move into and then rent out my current home or do I have to re-invest specifically in rental property with the proceeds from the sale in order to not be taxed on that money?  The reason I want to rent out my current home is because my mortgage is only $700/mo and the other townhouses in my association that are rented are getting $1250 a mo and they have not been updated like mine has been and $550 a mo for one door is too good to pass up.  

Another question I have is, if I do not re-invest the equity how much of it is taxable on the 100k if I put down 65k when I originally purchased the sfh?  All of it or only 35k due to the downpayment?  

Thanks for any input.

Shirley