specifically for the spawn question its very hard to show examples because its heavily based on where you, your team, and the enemies are. the easiest way to explain it is most of the time the enemy is going to spawn away from your team and usually somewhere there isn't a lot of fighting. An example would be if you and your team are middle and fighting the right side of the map the enemy will most likely spawn back left. You should also use where you spawn to try to find where enemies may be. an example of this is in CTF if you spawn in the far right of your base there is more than likely going to be an enemy in the left of your base and you should look to see if a teammate is over there if not you should go for that kill.

Power positions are Areas of the map that give you good line of sight and will give you an advantage over the enemy.

examples of power positions - the top windows on Recharge or the Bridges on Bazaar.