There is an editor action to select a line (Select line at caret) in the keymap that doesn't have a default shortcut, but you can define it and use it instead of the first Home+Shift+down. Then you can extend the selection with Shift+down.
Hmm... I've actually tried this but Shift+down unselects the initial selection. However, selecting a single line is still often pretty useful. I'll mess around some more with the keymappings to see if I can work something out.
b) Even then, I find it more error prone to reach over for the Home key, hit shift, etc...
c) 2+n is still 1 more than 1+n ([Ctrl] [l] [l] [l]). ;)
It's admittedly a minor thing; I just got really comfortable with Ctrl-l in Sublime. I should probably just get over it.