Câu hỏi của bạn quá chung chung. Cụ thể bạn cần biết những lĩnh vực gì, vấn đề gì bạn cần có câu hỏi cụ thể rõ ràng. Như khách sạn, ăn uống, hay quán bar....

I am also 60 plus. And prefer some nice atmosphere and cheap beer. Not noisy at least. Hard to find a pkace with acoutics music. Well head to the coffee shop with cheap beer and some nice finger food at the end if the stretch. However, be careful of con man

As a tourist I really don't know where is Rivergate, the most I paid for taxi is about 100,000 dong

While USD is accepted at quite a few places, you tend to lose out on the conversion charges. For eg. If your bill comes to a conversion of anything above USD 3 (even 3.1 or 3.2), you will have to pay USD 4. Better to pay in Dong everywhere in Vietnam.

I cannot recommend Viet Halal foods since found none very tasty. Coffeeshops are relatively expensive even starbucks which is near crazy buffalo. I cannot recommend and good cofffeeshops and had coffee as an instant at my hotel. Vietnam is not a very good touristy destination within Saigon. Careful of pickpockets and snatch ang run on moped thieves. Massage theft is also common. Bui Vien is just a street of very loud music from multiple bars competing using noise volume. Factually I cannot recommend anything to do in Saigon other than go elsewhere such as danang or some other beach city. Follow the Russians for a good time in Vietnam/

Sorry I do not know where in Ho Chi Minh City that can provide a professional, clean and decent tattoo. Just be mindful that Vietnam is still a third world country and many establisments such as tattoo parlors, massage parlors, beauty nails and hair do not practice proper hygiene nor are they checked and inspected by a certified Health and Safety to ensure they meet the standards. A friend of mine went to one of these establishments and wanted to have a few moles and spots removed from his face and the person was using a soldering iron. He was very lucky nothing serious happen. Just be careful and good luck!