Buying 2nd Investment Property

[Dan Del]

Hello - I have an investment property with substantial equity that I'd like to leverage for the down payment on another investment property.  

A.) Is this a product that exists? Do banks give HELOC's on investment properties, to buy another investment property?

B.) Timing is a concern - if approved and receive Line of Credit, will I need to start paying it back immediately? What if i haven't found the home yet?