Is the only way to pay for a Reno for my childhood home to sell my current home or is there a method I'm not familiar with that I can use my current homes value to help me out??

That's like asking how much it costs to buy a car. 

We are working on our first flip house and we didn't plan to do the BRRRR method, although it has come up in conversation multiple times due to the area it is in, we are still tossing the idea around of keeping it as a rental.

Find Brandon's videos on YouTube for the "four square" method of analyzing homes and practice.

Find Brandon's videos on YouTube for the "four square" method of analyzing homes and practice.

Are there any methods you want to stick with?

This depends on if you are using the Cash or Accrual method of accounting for tax purposes.

Is there any good rules of thumb to estimating the cost of a boiler?

Those holding cost will certainly add up over time and kill any cash flow.

For example, we've recently taken over marketing internally because the property management company was not experienced enough in using the newer advertising methods we need to pursue.