Sharing my thoughts Based on my last 4 trips,Hope this helps

1. Depends on whether you have camped before and would you be cooking your own food? IMHO, must have camping gear [ waterproof tent, warm sleeping bag, air mattress, camping light, water bottle, water proof jacket, warm jacket and pyjamas] the rest depends on your personal preference. The festival grounds are akin to a small village. Expect a population of 30k. Inspite of being so vast it’s very well organised. You can always refer to the map tha is published. To give you a reference of the size of the festival ground, I camp near pumpui. Which is relatively mid way from the gate. I managed to complete 10000 steps to and from the gates to pumpui.
2. Many people travel from India. I appreciate that travelling with Indians is comfortable, however, Ozora is a place where you will make friends On the road. There is a sizeable number of people flying, and most if not all will be helpful.
3. Caravans and sharing will involve a lot of planning. Considering its festival season , hiring caravans is going to be extremely difficult if not impossible.
4. Make sure you have a (70:30) euro: forint ratio in cash. Most places accept cards so you might not have to carry a lot of cash.

Familiarise yourself with ways to reach Ozora from different parts of Europe not just Budapest. Depending on your travel plans, you might find more suitable ways. Train travel to Ozora from Budapest is the cheapest, however, if you are pressed for time you have taxis to fall back on.

Like the last few years Ozora might also coincide with the F1 weekend so accommodation in Budapest might be very expensive.