Adding New windows (not replacement)

So, I've decided to add two new windows to the living area of our house. The wall currently has no windows on it at all, but opens to a porch on the rear of the house. The house is wrapped in cedar.

My question's are...
1) Should I use new construction windows or replacement windows? I'll be removing the drywall from the interior, but I'd like to keep this as clean of a project as possible.

2) What is the best option when it comes to ease of install? Buying two completely separate windows and butting them up against each other? Or buying a double unit? I would think that a single double unit would be easiest, but I've heard the opposite from some people in the past.

3)What's the easiest way to salvage as much of my siding as possible? I would rather not pull all of the siding down if I can avoid it, but I also don't want to cut away too much in an effort to get the windows installed correctly.


Thanks for any help you can provide.

Chuck...