Hello. I would be very grateful for some help.

1) Do you think the preposition "in" is OK in the following sentence or is it "after": "He knew he would return in a year"?
2) If a person left a building or a room, is it possible to say: "he came out of the hotel (room)" or "he went out of the hotel (room)"? If yes, is there any difference in meaning?
Thank you for all your great work.

3 answers

#1 -- Will he return within a calendar year? If so, use "in." Or will he return sometime after a calendar year is over? If so, use "after."

#2 -- Technically, you'd use "came" if you (the speaker) were outside the room and saw him come out. Or you'd use "went" if you were inside the room and saw him go out.
Writeacher is correct. I would add that if the person intends to return after the elapse of one year, you would say in a year, as in the case of he might intend to return on or about December 27, 2016. If it is a vague promise to return sometime after the elapse of a year, after December 27, 2016, after is a better word choice.
I would suggest that 'within' is the best option of all .
He knew he would return within a year