Get your financials sorted out first. It will cost far more than you think it will. http://www.remodeling.hw.net/cost-vs-value/2015/ Then, you'll need a plan to present to your city for permits. You can get that from a drafter, architect, or a design /build firm. The first 2 choices allow for cometitive bidding of the project itself, and the third chouce is less hassle to you, but probably slightly more expensive because of the lack of competition.

If the house has a good foundation, I would say go with it:) The decision is yours though. I have never built a house, but from what I have learned here, some of the less expensive builders limit choices - sometimes severely. There can be a choice of only a few cabinet styles and colors for the kitchen and only a few flooring choices etc. How much will it cost to get new hardwood and the good trim work your house may have? Maybe the inside is in very poor shape, but if there are well crafted elements, think about how much it would cost to replace them. If you go with what you have, you can work on it as you have funds and get what you want. If you think restore - except for the kitchen, your home will be cohesive, even if it takes several years. Are you far from Des Moines? You may have to go to a bigger city to get an architect. I am in Iowa and my countertop guy came a hundred miles to install my counters:) There are online resources for old homes: https://www.oldhouseonline.com/ https://www.oldhouseonline.com/articles/american-foursquare You can also look on Old House Dreams which has old houses for sale. Some are in bad shape, but some have been remodeled. You can filter the search (on the right hand side of the page) by picking "Prairie" because they don't have foursquare as a choice. Look online for forums and other sources for people who own and work on old houses. There are also bloggers working on old houses who blog about the experience. The most recent house being worked on in This Old House resembles a foursquare. The final wrap show is next weekend: https://www.thisoldhouse.com/watch/newton-generation-next-house My house is not nearly as old as yours and I did not have to redo plumbing and electrical. I did have to work on every room, some just cosmetic, some a bit more. Roof, windows, interior doors, floors, AC/heat - all had to be replaced. It was a run down renal when we moved in. I've liked not being limited by a builders choices of what I could do.

We have several of these structures in our neighborhood - the best ones have likely been designed by an architect as they thoughtfully match the style of the primary home (roof structure, windows etc) - but you may also be able to find plans online by searching "cape cod style garage" (**edit: just realized you want to access the top portion of the garage from the upstairs in the home - so you want to build an addition to your home that includes a 2 car garage? That would likely need an architect who is skilled with older homes and enjoys those types of projects (not everyone does) - we had several contractors pass on our addition/renovation project bc blending new with old is a PITA)

I thought the last two plans have the back door in the kitchen. Anyway, here are all the proposed plans with traffic patterns, prep paths, and clean-up zones. The first plan posted (whether the peninsula moves forward or not) is the only one with an efficient prep flow and no traffic through any work zones. Traffic to the fridge wasn't included because most of the plans have a beverage fridge on the bar run. I doubt the peninsula will be used for prep since it has no prep sink, but I added a sink and the green lines to denote that layout. I also added them in the second plan, as another poster suggested, but because the island is a barrier, IMO the prep sink doesn't add to function--and would put the prep zone in the basement traffic path. Even without direct access to the back yard, the first plan would be my choice. BTW, if the peninsula is only 3' deep, the seating overhang will be only about 10" since you'll need to account for a front overhang and a back cover panel. The NKBA recommends a minimum 15" overhang for seating at counter height, so an extra 6" depth would be more comfortable and would take up some of the dreaded dead space.