Using a monitor for MacBook

hey,

I have a MacBook Pro and I have a question about using a monitor.

I understand that I cannot use close the lid of my MacBook while connected to a monitor with HDMI without the Mac going to sleep unless its plugged to a power source.

the question is:

should I leave the lid up and dim the brightness to none while I'm using the monitor?

should I let my MacBook plugged all the time?

I don't want to play with the cables every time that I need to use my Mac... its really frustrating.

another thing, I find an article that said that part of the MacBook cooling system is in the keyboards, so using the MacBook with the lid closed and plugged in for along time really makes that MacBook hot, even the keyboards. I don't think that its healthy.

I hope someone will help me find a good solution for this problem :)