1. Hexes are "cubes with 6 sides" . CIV has Squares because they have 4 sides though it allows diagonal movement, so movement into 8 directions.
2. When you're surrounded by enemy civs, it depends on how bad it really is. Usually I like being surrounded, because conquesting land is easier and cheaper than peacefully REXing towards it. If one has no strategic resource though, the last is not efficient because it'd require to fight with Archers or Longbows, 1st are too weak and 2nd one require an enormously expensive tech that is off path, so 2. is better but still very bad, imo. only for experimental playing or when being very stubborn ^^
. 2-3 cities are ideal for an early breakout, if you mean that you are limited to only 1 city with being blocked, then you need to rush with Chariots or Axes, so with BFC Copper or Horses, even 1 city is feasible, 2 are optimal for up to HAs. Elepult 3, Maces 4-5, Cuirrassiers 6-7, Rifles 8-11 (all values for the earliest possible rush-date or highest amount of cities that one can / should settle when going for a specific unit) . To win a game, a lot less cities are needed, I once won a game where I went for a medieval rush, so Maces + Elepult, in which I was limited to 3 cities of which one only claimed Horses but had no
, so winning from 2 cities is possible 'til as late as medieval times on Deity, I also read from other players successfully breaking out with Cuirrassiers from as little as 4 cities.
Multifront-wars are not good until mid- to endgame, where one has enough military power. Try to attack one target with as much might as possible and focus on that target. Bribe another civ against it and wait 'til it has moved it's stack into enemy territory, then attack.