On the fit, just get something close to start with, make sure you are comfortable.

If you have not spent a bunch of time on a road bike, your fit after riding 6 months, 9 months, etc. is going to be drastically different as your flexibility and position change. A basic fit will get you close. Once you have a year or so of riding in, re-visit your fit.

On the weight, you are way, way too heavy (some would say fat) to be a competitive cyclist. Almost all of us are. I think my ideal cycling weight at 6'1" is around 150 lbs and I don't ever want to see that. Your weight will quickly be a limiting factor if you ride hills. You can only build power so far and then need to work on the other side of the equation. Just ride and enjoy for now, but don't be suprised if you start watching your like a teenage girl at some point. It's a cruel aspect of cycling. Luckily, you can quickly drop a lot of weight riding a bike. If you like having a muscular build, it can actually be hard to maintain if you're riding a lot.