It sounds like a solid plan on the surface but you are going to have to realize that having tenants right next door might not always be the best thing. You're going to have to think about a ton of "what if's." Like, what if they are slow to pay rent on time and you see them every day? What if their sink leaks and they are constantly knocking on your door because they know you're home? If you end up getting an awesome tenant, then it ends up being a wonderful investment. If you get tenants from hell, remember, they're 3 feet away. Good luck to you sir.
If you have good credit and 2 years of working experience and income, suggest you talk to a loan officer.
I like your idea. An FHA loan could get you in at 3.5% down payment for that House Hack. Unless you're military, then VA would obviously be the way to go. My first steps would be talk to a loan officer and determine what you could qualify for (either before you move or when you do move), and get a really good realtor that knows the area well and has found duplexes before. If you don't know the area well, make sure you find somebody who does.
1. I love the idea of finding a duplex. Live in one and self-manage the other side. This will save you some money and keep a close eye on your first property.
2. $4,000 is not enough to get started. I am not sure what the prices are in Iowa but I suggest saving enough for a down payment and have another $10-15k in reserves (could vary depending on avg price of the area). Never know what happens in life and to the property. You need extra cash just in case. Keep saving and don't feel a need to jump in.
3. I would get familiar with all the areas that you are interested in and see what prices are. Make a watchlist of properties you like and keep track of sold prices. Check what rents are for the area. You can look on craigslists and apartment sites to get an idea on rent comps. This will give you a good foundation on what to expect.
4. Find a 2nd source of income. This will fastrack your way to a down payment and to your goal of buying your first deal.