so, what was the retreat like. well, 5 hours sitting, 6 hours sleeping, then chanting, walking looking down, working and eating in a very ritualised way. very boring. highly recommended.
also there was a zen master, so we had interviews. i found that the master is using pretty same algorithm for every student. whether this approach is efficient i would need to think over and examine. also i doubt usefulness of some koans. this matter takes further examination as well.
i took 5 vows and now bear a buddhist name in Kwan Um zen tradition. the name is myo do, which means 'mystic way'.
finally, a tip for people who plan to go on a retreat for the first time: rotate sitting positions often. :)