Faster Than Light (FTL)
The ability to travel faster than the speed of light is, of course, impossible so FTL is a bit of a misnomer even in Galactica's world. Technically speaking neither Galactica nor any other "FTL" capable ship actually goes faster than the speed of light. What happens during a "Jump" is that the fabric of space itself is folded and the ship travels from point A to point B directly.
Picture space as a piece of cloth lying on a table Place a coin on the left hand side In order to move it to the right side of the cloth, you could slide it across the cloth or pick it up and place it there, both of which involve traveling across the physical space and will take time However, if you pick up the right hand side of the cloth and fold it over so it touches the left hand side, the coin can be transferred from one point to another virtually instantaneously.
That is essentially what happens during a Jump. Galactica's FTL engine fold the fabric of space itself (through another dimension beyond the 3rd dimension) and the ship literally transfers itself between two distant points which are momentarily brought together.
As a result, Galactica is never "cruising" through the universe as does the Enterprise or the Millennium Falcon. Galactica, and all FTL ships simply go from one point to another, and once they've arrived, they can only move at normal speeds below the speed of light.
Galactica is an older ship relatively speaking and so her technology is significantly behind that of many of the other ships in the ragtag fleet, hence the need for long checklists to be completed by many hands before any Jump.
The process is much simpler and quicker aboard Sharon's Raptor, for instance, but even the Raptor must make precise calculations and execute specific settings before initiating a Jump. (The specific checklist used by Galactica during the FTL sequence in the miniseries was gleaned from one of many checklists from the Apollo 15 lunar mission. Goto: http://www.hq.nasagov/office/pao/History/ap15fj/ and look under "Apollo 15 Documents" for many checklists of this kind.)
The speed of tight also governs communications and sensor information. The farther away a ship is from Galactica, the longer it will take the signal to travel If Galactica and one of her fighters are "only" as far away as the distance between the Earth and Mars (say, 700 million kilometers), there will be an 11 minute lag in a radio conversation. The same goes for optical observations in that by the time we spot a Cylon basestar-- at that same distance, it's had 11 minutes to move closer to Galactica.
The Cylons are bound by the same rules of physics and they cannot travel faster than the speed of light - they have to Jump as well.
The Red Line
Practically speaking the further one attempts to Jump, the more difficult the calculations and the more variables are introduces into the equations. For example, consider the difficulties inherent in Jumping to a relatively nearby star system "only" five light years away: any information Galactica can gather by looking through a telescope is, by definition, five years old. The star and all the planets surrounding it have been in motion for five years since the light we can see left that system This means that Galactica must calculate the motion of all the celestial bodies in that system based on information that is five years old. The further away the Jump point, the greater the problem - try to jump 100 light years, and you have a century's worth of calculations to do.
Because of the limitations inherent in colonial technology, their ability to calculate all the variables involved in a Jump are also limited. Their margin of error increases exponentially the further out they go and as a result, there is a theoretical "Red Line" beyond which it is not considered safe to attempt to Jump. At the end of the pilot, Galactica has intentionally Jumped past the Red Line and is in uncharted and unknown space.