1) Any decent start will do. Some hills, some lux, preferably no jungle. Obviously you also need horses.
2) Liberty is your best bet. Full liberty will grant you a GP. With it you either bulb chivalry or you rush national college.
3)Philosophy, Luxuries, and then Chivalry (obviously take its best requisites first).
4)No. Only get a pantheon.
You only need monument, libraries, granaries, barracks and maybe stables in your cities. Make some chariot, hoard some gold, upgrade all of them.
This is one of my favorite ways to play! I too do this on pangea. I play on Emporer.
Pretty much what Acken said...
DO go full liberty, use the free great person as a Great Scientist and bulb Chivalry with it. The sooner you get Chivalry, the sooner you get Keshiks. Once you've completed Liberty, then go with Honor.
DON'T build lots of your own cities. Keep your starting empire small, don't have any more than 3 cities. You'll need the happiness later. Wait to settle your second city in a spot with horses, and if you settle a third city, again make sure it has horses. The key here is to get libraries up and National College up ASAP to help you burn through researching to Keshiks. Be sure you get granaries and water mills if possible - more food = more population = more science = faster keshiks.
DO Build chariot archers and declare war on a city state or your nearest Civ neighbor. "Farm" experience for your chariot archers with the city state. DON'T take any cities yet, just bombard them.
DO complete City State quests if possible, especially barb hunting quests. Many obvious benefits here. Culture city states = faster policies. Martime = more science (due to more pop/faster city growth). Militaristic = more gold (sell the extra units they give you). Mercantile is good only for extra happiness, maybe they help you get an early golden age. Religious is pretty much worthless for this strategy.
DON'T spend gold on ANYTHING, get as much of it as you can, you're going to need it to upgrade them to Keshiks.
DON'T make any early DoF's (unless they are very far away from you).
DO sell excess luxuries for as much gold as you can get (in BNW, gold per turn obviously).
DON'T worry about wonders, tourism, or religion. You'll get all that stuff when you start conquering.
DO build 2-3 scouts early on. You need to know where everybody is to form your attack plans.
DO kill Alexander ASAP. If Alexander is in your game, he must be dealt with as early as possible, as his Companion Cavalry can give even your Keshiks fits.
DO raze every city that isn't a capital. Puppet the capitals you take.
REMEMBER - the keys are, EXPLORE EXPLORE EXPLORE, full LIBERTY tree, BULB great scientist, settle horses, prebuild chariots (or horsemen), farm experience, hoard gold, updgrade, and DESTROY EVERYONE.