Depends on the type of shul you are in. Young Israels usually do not do a “mi shenadar”. Some shuls have a minimum for a matana – look on the bimah. I know a shul that has a piece of paper stating the minimum for a matana (and it is less than $18). If you do not want this extra mi shebayrach you just let the gabbai know.
If you want to name people during the mi shehbeyrach try to have their names ready. Usually one does his wife and children. Some add on their parents and in-laws.
When leaving (or coming to) the Bima is their a correct path to take to/from the Bima?
One takes the shortest route to the bima. One takes the longer route away from the bima.
Does the person getting the Aliya uncover/cover the Torah? As a Baal Koreh I prefer to uncover the Sefer Torah when I am ready to show the person the place.
Open the Torah?
Yes, the Baal Koreh should open the Sefer Torah and show you the place. Some people place their tallis on the word and some on the side so they don’t rub the ink. According to the Shulchan Aruch (Siman Kuf Lamed Tes Sif daled (139:4)), you leave the Sefer open and make the first brocha. You close the Sefer before making the second brocha. The Ramah adds that you should turn your head to the left when making the first bracha so that the khal shouldn’t think that the brochos are written in the Torah. See the Mishna Berurah Sif Koton Tes Zayin – Yud Tes).
http://www.hebrewbooks.org/pdfpager.aspx?req=49624&st=&pgnum=38
http://www.hebrewbooks.org/pdfpager.aspx?req=49624&st=&pgnum=39
Scroll it ahead during leining if moving to the next column? As a Baal Koreh I prefer that person wait until I start unrolling the side I am holding since if you roll first you may start covering the words before I actually say them.
For Hagbah, you should put your hands as close to the round part of the atzei chayim as you can (for better leverage). Unroll so that 3 columns are showing, lbend your knes slightly as you start to slide the sefer off the bimah and then lift up. Lchatchilah you are supposed to make a 360 degree turn and then sit down.