@Gordana1165 Indoor makes it much easier as you won't need to get into the license issues. The project itself is not that big however you will need to detail every aspect and supplier in order to show that you have covered each area and are aware of what it takes to put on this type of event.
From what you've described you want to base your project on Squaremeals Venues & Events Live or EPS....have a look at these as case studies and see what you can take from them especially ticketing, vendors used, locations, dates etc.
You can 100% charge an admission fee but you would need to be smart with your pricing to ensure that the revenue can pay for some of the costs. The two events I mentioned above offer free admission however they make their money through the stands at the event and the model seems to work well.
Happy to offer any more advice....if the above is useful that is.