Josh,
The quality of advice given to you so far in this thread regarding sensible home defense has ranged from the detectably logical to the obviously retarded. I won't go into hardening you house against break-ins, but please read the following for a basic understanding of the firearms, mentality, and training needed to make a gun fight against a determined attacker not a coin flip.
I'm going to direct all my energy to the topic of guns. Some of this likely will look familiar to you, I've emailed regarding it before. I will not endlessly expound on the WHYs of these instructions in this post, but I will smother any nay-sayers who challenge this advice with FACTS and LOGIC.
Your rifle:
You buy an AR-15 in 5.56. The right barrel length is 11.5". the right barrel material is either Hammer Forged Steel or 1450 steel, what is important is the lining is chrome. Less so because I am expecting you to take advantage of its longer lifespan and durability and more so because it is an indicator that a manufacturer gives a shit. I'll let the mob advertise their favorite brands are that meet that criteria. Chrome lined barrel = probably fine. You start with the brace, you get a buttstock. You specifically shill out the $200 stamp to SBR the gun because you will be under intense scrutiny if something happens. Later down the line you buy a Silencer Co. or Surefire suppressor, as soon as funds are available and you have your head around how to take care of one.
You place on that rifle an Aimpoint PRO optic, a Surefire weapon light, and a sling. Regarding the optic, the PRO is affordable, and outstanding in all regards except weight. Do not deviate from brand, do not buy the Holosun some guy will shill instead. Regarding the weapon light, it is utterly retarded you need to pay $300 for a high lumen light with very good flood (lateral illumination) that doesn't break, but its the world we live in so suck it up. Regarding the sling, I like the Vickers Blueforce sling, but this is user preference. The suppressor is the single greatest upgrade anyone can possibly make to their gun, and borderline mandatory for serious use in a house.
You buy 77gr TMK rounds form either AAC or Black hills. About 300 of them zero you gun with these at 50 yds occasionally shooting to confirm zero. These are your "Oh shit its actually happening." bullets. You train with whatever the dirt cheapest ammo you can buy in bulk, sometimes they will be nice, sometimes not, but always fine. Buy 10 Gen 3 Magpul Pmags or Surefeeds if you can get your hands on them. You generally can't go too wrong with metal mags, but you can very easily go wrong buying polymer. Gen 3 Pmags are the only polymer mags worth buying.
Some important things to know, and how they affect your training:
People die from bullets due to exactly (and only) two causes:
>Central nervous system hit
>Dramatic loss of blood pressure
It doesn't matter how big the hole you put in them is if you do one of these two things.
People die from bullets in two ways:
>Flipping a switch (brain shot, heart shot), they are dead, or dead in seconds.
>Starting a timer (blood loss) they die slowly based on rate of blood loss/blood pressure drop.
You fire until you "flip the switch" any damage you do before that happens is massively beneficial to that end. In order of importance for achieving that:
1. Accuracy of the shots
2. Number of rounds hitting target
3. Particular terminal ballistic properties of the bullet once it hits your target
You rifle and ammo selection is a min-maxed solution out the gate.
How to think when you train:
Based on these irrefutable facts, marksmanship is paramount in a self defense situation. Your red dot optic will be simple to understand and improvement in speed will come with basic understanding of shooting stance and drill repetition. You need to group on an index card sized target, with the understanding that going too slow gets you killed. I'm not going to set par times here for you. It is a journey best started with little expectation in speed, and high standards for accuracy. (Side note: You shoot guys with body armor on in the face, or other places on them until you can shoot them in the face.)
Lights:
It is dark 50% of the time. So put a light on your gun. You want one that allows you to take in as much information, as fast as possible, prioritizing the information nearest to you. So you buy a good light with emphasis in brightly illuminating a wide arch instead of having light go really far out in front of you in a tight beam. You are NOT room clearing if you hear a bump in the night. You are grabbing your rifle and covering down the hallway/stairs/doors and calling the cops. You can keep the light on the entire time. Yes they will have a rough idea of where you are. Yes, it is better to see them first then risk it happening the other way around because your light is off or you end up blowing holes in your dog.
All of this is a few thousand dollars, totally manageable if done setting a pace for your spending. With this gear, monthly trips to the range, a good learning mindset, you will be not only well equipped to defend your swamp, but lay a solid foundation for many lessons and situations down the road.
Slings:
Keeps your rifle attached to your body when you need to do things or people try to take it from you. Very simple, but critical gear.
Your handgun:
9mm Glock with a quality weapon light and an RMR, ACRO, or Holosun. All of the things Glocks are great for are very important. All the things that make them suck are not that important.
For a civilian this is your primary weapon, and should be the focal point of your journey in firearms competency.
This is not a joke and I didn't get tired of writing. It is just that simple.