I think you're asking the right questions.
The only think I could add, is get a book on training to read up on before you get a dog, I never realised just how much training was needed until I got into, luckily I LOVE it and find dog behaviour fascinating so I do a lot of reading. There are a few good general books like dog training for dummies and rottweilers for dummies.
The more up to speed you are on potential training issues with a new dog (housetraining, destructiveness, nipping etc.) the better equipped you will be able to deal with those things. A lot of owners fail their dogs because they don't understand that "training" is more than obedience class, it's teaching a dog to live peacefully with the other animals in the house and be well behaved around people. Also,...being a "big" guy has nothing to do with being a good trainer
It's about being mature, fair and consistent. Anyone who keeps those 3 things in mind while training can handle any dog, no matter the size.
Also, another thing to think ahead about if you decide to get a dog is who would care for the dog if you had to travel for work etc. A lot of people get a dog not realising that even going away for a weekend means you need to arrange alternative care and that you HAVE to go home after work to let the dog out instead of doing happy hour with friends. Not that you can't do those things but I think the people that think ahead about that stuff (and plan accordingly for care) are likely going to have a dog for the duration of it's lifetime.