Welcome to the hobby!
I instruct quite a bit and highly recommend the previously recommended reading. These guys are as good as it gets when it comes starting out advise.
The "get an airframe that will help you rather than hinder" is also very good advice.
I would recommend the Sig LT 40 KIT ( since you said you want to build) and an OS 46 fx or ax. A 2 cycle engine is easier to set up and lighter and less expensive. I agree Saitos are really fine engines but maybe not for a first engine.....depends on the budget I guess.
BUT before you spend a dime know who is going to teach you and get there advice also.
It is a great sport for anyone. The friends are unbeatable.
A second option if you arereally into alternative low cost materials is the Spadet (a coroplast version of an LT 40) or the Debonair another coroplast trainer that has a history of being fine flying trainer. Spadtothebone.com has tons of free plans.