I believe the tools available will allow me to be succesfull in real estate.

Hi , I am buying a one family home, and would like to rebuild it from scratch, home is around 700k , rebuilding might cost 400k , I have enough 20% down payment and my dti ratios allows me at 800k conventional,Whats the best should I should do for this home?

Not needed if buying for what is owed plus arrears.I've been a landlord for a while and I don't allow smokers or growers of any kind no matter the higher rent.

You will need a place to put it, and if you don't already have land that will allow it you need to find a Mobile Home Park.  

Usually no more than the allowed 43-45% back end ratio.

Most states do not allow you to play both parts with the same client. 

Some REO properties will not allow you to sell (make money) for a certain time frame.

The first purchase I would like to use the FHA program, thus allowing me to only put down 3.5% for the property then rent out the other three units.

Usually either a short term loan with goal of owning free and clear in 4-6 years (no cash flow, let the renters earn you a free and clear house quick) or a 20 year term allowing double digit cash on cash returns.

Then, my inlaws have agreed to take out an equity line of credit on their house and are going to have a little more than 40k in money that they are going to allow me to use.