You are on the right road. Hiring professionals is very important on projects of this scope unless you are on very good hand -e-man.
You did not give us the name of your community. If you live in a large city, you have more options than if you live in a town with one architect.
First, you need an architect who is versed in residential archtecture and residential projects of your scope. Altho good designers are good designers, many architects get involved with one or two types of constuction. To ask a large firm who does skyscrapers to work on your project at a reasonable cost is not going to happen. Look for a small firm, even one-man firms who like to work on projects such as yours.
Next, ask if they have experience in doing projectds such as yours. Then, ask if there are projects in your area that you could review, and, talk to the owner. See if they liked what happened and if things stayed within costs.
Then, ask for a fee structure. Send your list of possible architects a fax of your house and a rough sketch or description of what you want to accomplish, understanding that a good architect could find a better way than your pre-conceptions........down the road you need to stay flexible. Then, ask him what he thinks the cost of the project may be and a range of fees, including the structural engineer.
The important thing here is to let the architect be the guy in charge.....be polite, and ask for "his" opinion.......after all, you are going to pay for it. Nothing is more frustrating than a client who "knows" everything and then hires a professional to listen to "him".
You want an architect who you can communicate with. Communication is very important for any project.....like a marriage, without it, you ain't gonna have KaKa.
You can get more options by talking to the building inspections department of your community. You can ask them for a list of residential architects in your area. They cannot give you "their" preference, but they usually don't include architects they feel are a problem. So, you get what is called a "short list".
Also, you can go to the local residential builders organization and get names of architects who are in line with your needs. Talk to builders who do homes in your area that hire architects. And by architects, I don't mean some kid who couldn't finish sc