Exactly how far can a jump pack? What considered a base move? This rule seems very vague and open to interpretation? is a run or a charge a base move? cause i imagine jump packs being used to charge with?

Core, Pg 171, "A Jump Pack requires the Pilot (Personal) skill to operate effectively. An Astartes Jump Pack allows for a safe, guided fall from any height, and any number of short jumps. Such jumps allow the Battle-Brother to double his Base Movement and travel in any direction without regard for obstacles. For all other purposes, he counts as having taken the appropriate Movement action."

Table 1-3 shows your base movement (pg 27). If you had a Space Marine with a base Agility of 41, he would have 5 Half Move, 10 Full Move, 15 Charge and 30 Run (Note that the Space Marine’s Power Armour improves his normal Agility Bonus for calculating movement rate by 1). Whenever a player chooses one of those actions, they double their movement. If your player chose to charge an enemy and has an Astartes Jump Pack equipped, he is able to charge 30 metres.

A jump pack DOUBLES your normal movement rates.

A character with AB 3 has normal movement rates of:
3 half (AB)
6 full (ABx2)
9 charge (ABx3)
18 run (ABx6)

If this character had a jump pack (and required skill) those rates would DOUBLE to:
6 half (ABx2)
12 full (ABx2x2)
18 charge (ABx3x2)
36 run (ABx6x2)

You do not have to use the jump pack to move, instead using feet normally (and thus no doubling). Using the jump pack ignores any obstacles which would not obviously block flying through the air (like a low wall, store sign, trees, or massive swarms of flying creatures; use the common sense rule).

The jump pack can also be used for true flying (normal jump pack movement is just jumps and hops). When using the jump pack in this manner the character gains the Flying (12) trait. The character may fly as a flyer with the following movement rates (these can NOT be doubled by a jump pack, you're already using it to fly):
12 half
24 full
36 charge
70 run

The jump pack can only be used in flying mode for ONE MINUTE. Then it must cooldown for one minute.