drinking water, banking and Amazon delivery (Ulaanbaatar)

Sain baina uu. I will come to Mongolia to live and work and first do an exploratory 2 month trip to sing all over the country with Mongolian musicians and stay with Mongol friends and to see where is the best place to live and what kind of job opportunities are available. Mongolian friends have advised me that they will help me open a bank account as most businesses do not take US credit cards. Does anyone have any advice about how to carry cash safely to Mongolia or to access my US bank account while in Mongolia? It used to be easy with travelers checks, now most banks do not offer them. I also was informed that I will need to get a Mongolian cell phone as we cannot charge our US phones. I am double checking for advice on this. I am used to traveling in Central and South America where we cannot drink the water, ever. Can I drink water in the cities and in the grasslands or does it need to be boiled? I am getting differing opinions from Mongolian city and nomad friends. Lastly, does Amazon deliver to Mongolia? I appreciate any advice on these questions. Naomi