Can we take the star ferry from kowloon going to HKIA?

I'd tell you that Star Ferry doesn't lead to HKIA. You may walk east for about 450 yards, and turn right. Walk south for about 200 yards to Metropark Hotel Kowloon. Then, take free shuttle bus line K5 to Kowloon Station. Afterwards, take Airport Express Line to HKIA. It takes about 20 minutes, and the fare is HKD 90.

You may arrange your itineray this way if you have three whole days:
June 30: Ladies Market- Tsim Sha Tsui & A Symphony of Lights- Temple Street Night Market
July 1: Ocean Park- The Peak- Lan Kwai Fong
July 2: Big Buddha & Po Lin Monastery - Disneyland Resort

For transportation, the ferry doesn't work. You can use shuttle bus instead. Walk from your hostel to Grand Tower, Nathan Road and take no. A21 to the airport within an hour. The cost is 33HKD per person.