all that happened years ago - years before Kitty met Sherlock, which was 2-3 years before this season 5 ep. Gruner was not the father.

in "M" there were tears when he said "I'm going to miss this…but this; working with you." In "No Lack of Void," tears at Alistair's grave. And in "The One That Got Away," he was crying in the flashback when Kitty returned to say she wanted to keep working with him.

he has shed tears on screen - 1x12 (in front of Watson no less), 2x20, and 3x12 come to mind.

Remember that Sherlock was happy to have lessons from Alistair because his Derry accent wasn't good - he would absolutely welcome notes from a native speaker to improve his Cantonese. At the very least he'd want to know if it would be easy for native speakers to identify him based on how he spoke the language.

except she didn't know he'd written a crime novel. if she wasn't a regular reader of the genre, she'd be unlikely to come across it on her own.

the only episode without any deaths or dead bodies at all is 1x15, A Giant Gun Filled with Drugs.