How long should I grind coffee beans to get the full aroma without it tasting bitter?

Not long. 10 pulses or so.

Add a pinch of salt to ground coffee before brewing. It will eliminate any bitter taste.

Actually, coffee beans should be ground so you get the best flavor and aroma from your coffee make. Most coffee makers will tell you in the instructions which grind you should use. Some of the better coffee bean grinder might also tell you in the instructions. I believe my Cuisinart Coffee Grinder did. I know that I use a medium-fine grind for my Chemex coffee pot and a medium grind for my electric drip coffeemaker.