Welcome aboard.
Your height is going to be a bigger problem than your weight. 250 is not really all that much. Unless maybe you live in really mountainous territory.
But even your height won't be too much of a problem. I'd advise getting a long seat post. A lay-back style will come in handy, too. But make it long so that it goes down deep into the seat tube even when you've got your seat up high.
Here's something that'll seem counter-intuitive; I'd get some heavy duty 24 inch, yes....twenty four inch....wheels. I just recently made that switch myself. And I'm happy with the results. My 'footprint' on the road is definitely more stable. And those wheels are stronger because of both the stouter spokes and the shortened diameter. I'm six feet, zero inches. But those shorter wheels haven't brought me down as low to the ground as I'd feared. And you'll be able to be comfortable with that long seat post.