Currently I recommend choosing comics that you WANT to feature. Comics you enjoy and that you love. Maybe even comics that your readers would enjoy because it falls into a similar category.
If you choose to feature something you are not really behind, your readers will notice and stop trusting you.
To track the success of your feature you can use bitly.com as recommended by Michael - it is incredibly easy to set up and took me all of 3 minutes.
As for contacting the other creator I recommend dropping them a quick note, telling them you would like to feature them, maybe even asking for a picture you can use. Or you don't tell them and surprise them with it. If someone complains about free advertising, then nothing can help them ; )
I will combine the data I was able to collect soon. (It's not too much right now)