What are the visa & residency requirements in Turkmenistan?

"In order to visit Turkmenistan, travelers must obtain a visa prior to arrival. The process of applying for a visa involves submitting an application form, a valid passport, two passport-sized photographs, and a letter of invitation from a Turkmen host. Depending on the purpose of the visit, additional documents may be required. In order to obtain residency in Turkmenistan, applicants must submit an application form, a valid passport, two passport-sized photographs, and a letter of invitation from a Turkmen host. Additionally, applicants must provide proof of employment, proof of financial means, and proof of health insurance. The application process may take several months to complete," said another expat in Turkmenistan.