Well, glad I got that out of the way.
So, life has landed me in a place where owning/maintaining a car is undoable but fortunately for me, unnecessary. The commute to work is short. I am excited about the prospect of viewing the world without the frame of a car windshield.

So I need a bike and I think I have found the one I like, and as much as I would love to support my local shops, I need to be extremely frugal so I am buying online. Maybe not the best idea but they have the bike I (think I) want, cheap.
My first question concerns size:
Is sizing pretty standard based on how tall one is? I'm about six ft tall. I see options from 50cm to 62 cm. What should I choose? Or is this a very subjective decision?
Wheels:
After some cursory reading, I understand that frames aren't an issue for us larger types so much as wheels. I'm around 260 lbs. What wheels would you recommend?
Are there any other essential upgrades that are considered essential for clydes? Maybe a saddle?

The ride I am considering is a single speed. Am I crazy? When I mentioned it to my family they reacted as if I was buying a camel. How have you larger guys/ladies fared using a single speed? My commute is short, but it's somewhat of a climb toward the end, nothing to bad though. I'm fat, but I'm not a complete slob. I work in the trades. While I'm strong, anything having to do with endurance..kinda..well, it turns me into a slobbering, sweaty mess. But I'm hoping to remedy that.

BTW, the bike I am strongly considering is a 2011 Jamis Sputnik. Sexy looking bike and it came strongly recommended by a bikesnob friend. It may seem foolish to purchase a bike without riding it first but here's how I see it: I am such a newb that I don't even know enough to know what's comfortable and what's not. I doubt I would be able to discern the subtle differences between one ride and the next. So I'm just gonna make the plunge.
Thanks in advance.