That depends on a couple of things. The most important and practical concern is whether the house was framed with roof trusses or stick framed

With trusses, they most likely span from fron to back walls and all interior walls are non-load bearing so they can be moved about or taken out.

The second concern is similar in that you local permiting agency has the job of reviewing plans to see if they are structuraly sound and the place won't fall in on itself or anyone else. They may be able to OK hand drawn plans from you or they might require an engineer's or architects stamp on them. The local permit office is the place to start.

Excellence is its own reward!

i have worked on a ton of ranchburgers... not too proud to say! true to look at the trusses but that doesn't answer your question! here is how to look at it! first take pictures of the ceiling trusses and just sketch the rough floor plan.. yes it can be horrible but understandable. next call up a local architect and a local designer as well as a contracter. they should all assit you for free and should be at least eager to look at what you have. in my opinion the permit office is an unholy place to someone who has little knowledge of architecture. remember always to get opinions from several people. if you only goto a contractor be sure to goto a few different ones. they can be ahhhhhhhhhh zealous to say the least!

Porti,

I'm curious why you would expect that a design professional should be eager to offer his service for free. I rarely hear of other professionals like doctors, dentists, or lawyers doing free work like that. How would they make a living that way?

Excellence is its own reward!

nothing my friend is for free. designs, plans, and stamps cost money. but asking someone to look at your project is not out of the question. i have worked at places where people look at stuff and help people along cause they are people; not money crazed uncaring thugs. i realize you are making a try at the design professional thing and do not like architects so much. you totally forget that people are people. maybe one day the sprouts of compassion will find its way into your heart and you will be able to rejoin the human race. until then i would recommend you goto school and do real learning on design and not armchair contractor work! architecture ethnics class is a bonus that may help you along!