Haaa, if only you weren't living on another continent - we'd be having soo much fun at the range!
First of all the most important thing is that you try out guns before buying them to see if they ergonomically work for you. You're a Big Guy after all. Try several models, not everything that looks great feels great in your hands. Check if you like the sights and the trigger, people are different. If you can shoot them at the range before buying.
Then book a course with a shooting instructor and get some hands-on training, regularly train at the range and at home. Especially muzzle and trigger discipline. This is absolutely essential! The best firearm is not only useless but an outright hazard if you are not proficient at handling it. Once you got this, book advanced courses at home defense to make sure you tactically and legally do the right thing in a SHTF situation. Not having any prior experience can also be a blessing because you don't have to un-learn bad or dangerous routines you may have picked up without professional training.
Be sure to familiarize yourself with local gun laws and follow then to the point. There's no room for 'creative interpretations', no matter what more seasoned shooters may tell you. With great power comes great responsibility.
You should oviously also be able to do cleaning, maintenance and basic repair which shouldn't be a problem for a mechanic. It's really not hard, we easily learned do that now for our 10 different firearms and have built two AR-15s from scratch.
Regarding models, the DP-12 is a beast! Never seen let alone shot one because it's too short to be legal here. Would buy immediately if we could but even we can't. I don't think you can do much wrong with this gem. I'm already jealous!
About handguns, it's really up to your preference. I suggest you try several and see which you like best. I, law enforcement and military go with Glock, it's a masterpiece of engineering, simple and very beginner-friendly. Inherently safe trigger that can never go off if you drop the gun, no safety needed. The Glock 19 is probably the most popular gun for concealed carry worldwide - for a reason. Of course the 1911 is also a great gun but you must never forget to enable/disable the safety even under stress situations. Not a problem with adequate training but you need to be able to do this unconsciously and flawlessly or else there will sooner or later be a severe problem of you forget. Glock vs. 1911 is an endless ideological war, just try both and go with whatever you like best. 9mm is a good beginner round, cheap and easily available.
Oh yeah and if home defense is your main objective be sure to get simple and popular models that have sufficient spare parts available and buy those in advance. The last thing you want is a gun that's useless because you lost or broke some tiny spring you can't get anywhere. Oh yeah and buy ammo. Lots of ammo in bulk. Like 1000 rounds. Seriously. It's much cheaper and you need far more for training than you think. You easily shoot a hundred rounds on a serious range day. Also ammo doesn't go bad, lasts forever. Buy the cheapest stuff available for the beginning. Paper targets don't need hyper-modern expanding bullets. I can't tell you much about best self defense ammo though because I don't routinely shoot peopleyet