He can control his emotions up to a point - that's part of what was great about Gosling's performance IMO, that he was able to convey how K was having to keep his emotions constantly in check (and occasionally failing - the fight with Sapper and at Ana's lab) due to the consequences for him if he failed a baseline. By the time of the second test, his whole world as he knew it had fallen apart. Joshi didn't know about any of that - all she knew is he was supposed to be doing his mission and he was picked up outside an upgrade centre and might be'going 'rogue'. She's only mad at him until he confirms that he had done what she asked,, and she is then relieved and becomes more concerned for his situation.
The music from the trailer was a reworking of the original score - that composer was removed and replaced by Zimmer and Wallfisch a couple of months before release. Their score is still synth-based (and the Yamaha CS80 plays a large part in it), but has a far heavier and more oppressive atmosphere than Vangelis' score for the original (though they do quote his score for one key scene)
The original is my favourite film too - I've owned all the versions since my first VHS in 1987, and have watched it well over 100 times over the years. I too was very worried right up until I heard Mark Kermode's (BBC) review. He is also a big fan, and made a documentary for Channel 5 in the UK about the original that made it onto some versions of the DVD.
https://www.youtube.com/watch?v=g3mq-1jcFzk
He was also worried until about 20 minutes in, when he realised they had got the tone and pacing right and he loved the film. Based on that I went to see it, and wasn't disappointed - I ended up seeing it 5 times at the cinema.
https://www.youtube.com/watch?v=ba8OIbWEHQM