How much do you think is reasonable? Probably you should give more details. Anyway, I’ve found two hotels near OCT East (Shereton and Pattaya).

Jordan to Luo Hu: around 52 minutes. Luohu to OCT East:

Any special on-way transport (eg bus express) from Hong Kong direct to OCT East?

You can take direct bus from HK to Huaqiaocheng in Shenzhen at Mong Kok CTS Branch. It costs around HK$40. The last bus leaves at 10:30. Then take sightseeing bus line 1 to Dameisha.

How long it take for sightseeing bus no. 1 from OCT east to Window of the world? And is the bus available every 1 hour? Do I need to buy the ticket in advance?

It takes around 40 minutes. The bus runs every 8 to 10 minutes from 07:00 to 21:00. Ticket fare: CNY 2-10. You needn’t buy the ticket in advance.

Which hotel recommended in Window of the World with reasonable price?

7daysinn and city inn. Both are close to WOW.

Is there bus service from Dongmen to Shenzhen airport? If yes, how much it cost and how long it take?

Take subway line 1 at Laojie (Old Street) to Kexueguan (Science Museum), exit B and go to Hualian Building to take airport shuttle bus to Shenzhen airport.