Help: super low action – does it affect tone?

I recently pushed a EBMM JP guitar and I love it love it love it. However, I noticed the previous owner had the action very low -I think as low as you can go w/o fret buzz. This brings up three questions:

1) Typically speaking how does super low action affect tone – specifically does it bring out the highs more then the lows? I’ve noticed this guitar sounds somewhat bright through my amp. Raising the action will affect the tone how?

2)I’m going to adjust the action myself – counter clockwise raises the action is that correct?

3) I’m debating raising just the high strings as the low strings sound fine – is there any problem or headaches that come with raising one side and not the other? I haven’t decided but I may raise it even across all strings just want to keep options open.