Tourist visas are usually valid for one month only and can be extended for a second month, for example at the Central OVIR office in Bishkek, although – in effect consular officials issue a new visa to run consecutive to the first. At the Central OVIR office in Bishkek, you have to write a letter of application (in Russian) giving reasons why you want the extension. However, the officials have been known to decline to renew a visa. A tourist visa does NOT grant the bearer the right to employment in the country.
Technically, it is not possible to convert a Tourist visa into an "Ordinary" visa.