I believe the optimal amount of time spent on these other activities is as little as possible.
Graduate students are notoriously overworked and underpaid. In essence, they are trying to see how much work they can get you to do for them, for free. In situations like this, where they attempt to get you to prove how much of a 'team player' you are by essentially providing them valuable work without them having to pay for it, you need to be on your guard and make sure you aren't taken advantage of.
You will need some of these 'extra-curricular' activities. But they are a means to an end. Essentially you must demonstrate your willingness to go 'above and beyond' the explicitly listed duties of your job without neglecting the official duties. It can be a tight balancing act.
There isn't a hard and fast ratio, like 70% research/ 30% leadership. Instead, you will need to be skilled at determining your peers/superiors expectations for you in this regard and meeting/exceeding them, and this will vary from institution to institution and individual to individual. A lot of potential feedback is likely to be of the 'you must read between the lines' variety.They are unlikely to say "You aren't going to get the position unless you do more work for us for free". Instead they might hint "you are doing great in your research, but it would be very nice if you would take more initiative and perhaps be more of a mentor to younger students" - indeed, anything phrased as definitively as that is equivalent to being posted in bright red flashing letters.
In general you will be pressured to spend more time on these activities than you can afford to, or is necessary for your career. Finding out where that level is (somewhere between 'nothing' and 'everything they ever ask you to do') may be a matter of trial and error.
I would spend time on the research unless you get the distinct feeling you are not meeting expectations in the extra-curriculars department.