Welcome to the boat mate.
#4 is a real problem. See this thread:
http://www.subsim.com/radioroom/showthread.php?t=159568
I would not even mess with it.
Start a war patrol, Wounded Bear or Hellcat. Don't worry about completing the mission. All you want to do is find a single ship.
You will have radar so just go to the Luzon Strait above the Philippines.
Just plot a zig zag course in the area between Manila and the strait.
You will find something soon. A single merchant is best for learning.
Once you make contact with radar turn towards the it. You will see that it seems to jump ahead. when it does start the stopwatch and mark it's position on the map with an X. Wait 3 minutes and mark it's new position.
Measure the distance between marks. You should get something like 900 yards more or less. This will give you the speed of the target. 1 knot of speed for each 100 yards, in the example 900 yd = 9 knots. I do this at least three times, that gives you a good reading of course and speed.
Next draw a line through the marks and extend it in the direction of travel.
This will give you it's course. You than can plot out an intercept course that will get you in a good firing position, ahead and to the side. Point your boat about 80 to 90° from the course line about 1000 yards away.
You have the target speed so all you need now is AoB and range/bearing. Since you have already done mission 3 you should have some experience doing this, You should be in about the same position. If you are using auto targeting all this is done for you.
Save the game when you first make contact and you can replay it and try out different methods.
This method works with escorted convoys as well, plot their course and set up an intercept the same way but you will want to be farther off the course line. you can either go deep and let the lead DD go by and than come up to PD and set up an attack or I most often just stay at PD and shoot from longer range. I approach the convoy at about 70° to get clearance from the flanking DD.
Mobucks method is a very good way of tracking and attacking if you have map contacts off.
Heading is just that the direction your boat is heading. if North your heading is 0° on the compass. Your coarse is from south to north
Turn 90° to a heading of 90°(east) and your course is from west to east.
Bearing is the direction to your contact.
"Contact bearing 245 long range".
That means that the contact is 245° off your left side about 8:00 on a clock. your periscope is a bearing tool. 0/360° is the front of the boat, 12 o'clock. 3 o'clock is 90° to your left etc.
Hope all this helps.
Magic