Capital: formerly Dar es Salaam, but it is now transferring to the smaller Dodoma
Transport: there are buses that connect major cities. But I’d recommend flying between Zanzibar and the mainland, and getting shuttle around by tours or safari company.
Currency: Tanzania Shillings, but they also take USD sometimes. 10000 shillings = 4.3 USD = 30 HKD.
Sim Card: people recommend Vodacom or Airtel sim card, which you can buy on the ground.
Handy Apps: Google map works well for Tanzania and most tour operators will communicate via whatsapp.
Language: there are three official languages in Tanzania and one of them is English. Swahili and Arabic are the other two.