Like you said; your body fat % has to be really low so if all you're aiming at is having six-pack abs go for daily cardio or HIIT and a diet (just a small reduction in calories, nothing too drastic).

Crunches and hanging leg raises will help, but only if you drop the fat.

I know its extreme but i found when i want a six pack i completely cut carbs from my diet. It leaves me feeling tired and grumpy but can usually has a six pack within 3-5 weeks when used with a full body exercise program and fartlek training.

I'm not a big fan of no-carb diets. In my opinion the risks outweigh the rewards.
When I cut I can usually lose anywhere from 2 to 4lbs per week, so it takes me 2-4 weeks to do it with a normal, balanced diet to get there.

Ok THX mate!

No problem :)

Well, i do not have a sixpack myself, might be i had one in my skinny days, but my best advice is training like swimming/running while taking upper body exercises once in awhile

dont do too many tho, because everyday is abselutely not upper body day

Any time.
Good luck!