1: you can move a group as far as you want as long as you have command. Question is say it takes two command to move through a planet with sarkeen regency. Can I move on past it as long as I have the command or must I stop and fight it as I’m moving through?
You are never forced to stop in a particular space by any effect other than running out of command - you can pass through a space with the Sarkeen Regency token without fighting it so long as you don't stop there. (The rules only state you are forced to battle them if you end your movement there.)
If you end your move on an inhabited planet with a Sarkeen Regency token you would only be forced to fight it if you chose to stop on the capital section of the planet rather than ending your movement in orbit.
So the only situation in which you'll be forced to battle the Sarkeen Regency without having explicitly decided to do so is if you try and move past an uninhabited planet with a Sarkeen token on, but fail your roll to move past a hazard and don't have enough command to move away in any other direction. Then you'll be forced to end your move on that uninhabited planet, and thus be forced to battle.
2: the rules state you can not drop off units and continue moving. What if my group started to move and they all started on the world ship, can I leave any behind?
At the beginning of the move action rules, you'll note it says you can move "a number of units" from the start region - you can pick how many to move and how many to leave behind, you just can't drop units off as you go.
3: when I move can I move more than one group? Ie spend 2 command to move world ship and then one command to move sloop?
No. Again, note that the rules state you are moving a number of units from one region. That word is bolded in the original. In the glossary it clarifies that you cannot move more than one group in a single action.
4: when moving a group I can only claim a planet if it stops moving, meaning once claimed I can’t continue to spend command points and continue moving it?
Yes. You may only make one attack per turn, and it occurs after you have finished your movement.