Is it possible to get my visa from the embassy in hanoi? What should i prepare for it? the cost?

Yes, you can apply from Chinese embassy in Hanoi. For mainland kind, you should submit your passport, application form, a recent passport photo, round-trip air tickets and hotel booking. For Macau entry permit, the requirements are similar. You need to provide your accommodation, flight itinerary and travel itinerary proof. Besides, financial proof including pay slip, recent six months bank statement and tax receipt.

For applying a single entry mainland L type, it costs 30 USD. For HK, the embassy doesn't specify the cost.