Did you click on your own ads or tell your friends to click on them? If not then no you don't have a problem. Even if you've been click bombed google will be able to sort out the bombing. As long as your clicks are legit then you will be fine.
It also depends on how many page impressions and clicks go to make up that 30%. This can be effeted by how soon in the day the impressions/clicks have happened. For example: If you have only had 3 page impressions and one click, that would translate to 33.33% CTR. That's fine. If you have had 1000 page impressions and 300 clicks, that would also translate to 33.33% CTR, but would look more suspicious. Things should even out as the day goes on and CTR come down. Look at the CTR% for the whole day, or better still, the whole month. If you continuously get 30% it will cause Google to check out your site. Even then, if the clicks are genuine it "should" be OK, but hitting 30% regularly is pretty unusual.
Depends on the volume with relation to the CTR. I think their is a point where google will view you as highly suspicious.
normaly its not a problem it would consist in a problem if u hav 100 ub from wich 30 clicked ur ads but if everithing went acording 2 the rules then theres nothing u should worry about