Also, how much tax do aircrew normally pay in Hong Kong or does the company take care of it.
Don't make me laugh. The standard rate of tax in Hong Kong is a flat 15% of your taxable income. There's also a sliding scale of rates that favours those on lower salaries. Aircrew normally earn too much to come under the sliding scale, so their income is taxed at 15%.
Hong Kong also charges 'provisional' tax, so your first tax bill can be quite high. It will include the tax you owe on the income you've already earned, plus provisional tax for the following year's income.