Read Avery Carl's book.

i'm reading it as well. you can always call township yourself and ask hypothetical questions. dont share your address

It's a tax on the gain.How is this calculated?

This question seem pretty naïve for someone that's flipped about 30 houses. 

The only source for all the local information needed is an experienced local team.

Meet ups could be a good source too since you’re in a big market. 

Seller will owner finance the portion she can.To those who have been walking down this path, how are you funding these projects?

So the problem is you wont be able to source the down payment as coming from the seller (most likely), but you can certainly add as many junior lienholders as you like, after the fact.

And if this is illegal in some states...what exactly is illegal about finding interested investors and matching them up with a funding source?

Hello Mike, It is nearly impossible to answer this question without taking a deep dive on the numbers of each but often times in expensive markets like Seattle the cost of construction is so high that it doesn't make sense to tear it down unless you can build something way bigger/nicer.