I was thinking of moustache or albatross bars for the my current bike, but I'm not sure how to work it since I have handlebar shifters.
A-bars are more comfortable than M-bars, in my opinion. A-bars keep you more upright, while M-bars get you in a more traditional position. You could use brifters on the M-bars, but not the A-bars.
(BTW, if you don't need bar end shifters, Dove bars are a more affordable alternative to A-bars. The shape is very similar.)
1. narrower, high pressure tires waste less power
Bicycle Quarterly has done some research into this, and found that high volume/lower pressure tires aren't necessarily slower than their skinnier counterparts. You don't need to rattle around on 23mm tires pumped to 150psi to go fast.
(I suppose, though, that one person's skinny tire is another person's fat tire. Some people think that 28mm it "fat", while others might say "too skinny." For all around, generally fast riding, I'd run a good 28mm tire.)