Dan won't appear until you have done a couple of tasks for Sviblov.
I don't know why Cold and Syslov won't talk to you, but it may be because you didn't visit the base immediately after helping Lector. Try again after doing Sviblov's tasks. Were you able to talk to Vasily the repair man?
Some of the recorded (spoken) dialogue is in Russian and some is in English. However, all tasks and other important information can be found in the written text, which is all in English.