True, if the virus is transmitted through blood, melee would be a bad choice.
If you must go the firearms route, make shift firearms would probably be your best bet as well. Like a modified nail gun or something, but I'd say a good ol shotgun and perhaps a 9mm handgun should do the trick since ammunition is usually plentiful.
Revolvers are too slow to reload and usually have a lot of recoil making follow up shots difficult, and if the zombies are anything like in Left for dead, you're screwed. As for not caring for other survivors, the ones that can make it more than a day or two are worth keeping around, your chances of surviving I'd imagine would be much higher than going it alone or even with a smaller band (Provided you've found a suitable place to grab supplies).
I'd also imagine that staying in one spot for too long would be a very bad idea, especially on top of tall buildings with no other exits other than down if you were to get swarmed.
Guns really, I'd have to say go Russian or go home, the Russians got at least that much up their sleeves, their guns are designed to fire regardless of their condition and can shoot almost any ammunition. AK47/74, Mosin Nagant, and SKS' have plenty of surplus ammunition, so they'd make an ideal zombie apocalypse firearm IMO.