This is old knowledge the playing with an unlocked screen. Around 2 years ago the screen was set up in such a way that as the red team your camera was always "off center." So you would see a large portion of the map behind you compared to the small portion in front of you. It was a major disadvantage to be on the red side and to combat this people unlocked the screen. Riot has since fixed this so as to be more uniform in how it shows the area around your champion regardless of what side you play from.
Nowadays, unlocking your camera allows you to freely pick and choose where your vision focus is. So when you have a champion like Jinx who has a global range ability in her super mega death rocket it helps to unlock your screen so as to increase your accuracy on the ability. You can also unlock the screen temporarily to check up on other lanes to see how they are doing.
Generally by the time you hit level 3 or 4 people are capable of contesting dragon. Generally around 8 minutes a ward in dragon pit is appropriate and by 10 minutes you should most definitely have it warded because by that time people are reaching level 6. Otherwise you just want to ward your flanks and side brushes.
Top lane is generally your tanks and fighters. There are exceptions where some marksmen or mages end up going. But usually these are melee oriented lanes where you play your most durable champions. Mid lane is typically mages and assassins and the reason why these types of champions go mid lane is because they scale better with level rather than items and because they have the most freedom to roam. Bot lane has two players in it, generally a marksmen and a support. Marksmen are ranged champions who are weak early but scale really well into the late game once they start getting items. Supports are generally tanks or mages who are there to babysit their marksman in order to get their marksman snowballing. The reason why you send these 2 bottom is because it is closest to the dragon pit which is always a highly contested objective.
The general all purpose summoner spell that works on everyone is flash. It instantly moves you from point A to point B, so you can use it to dodge an enemy ability, get around an obstacle or to close a gap on an enemy. It is generally believed to be the best spell in the game and rarely will someone opt out of using it. Ignite is generally used by mid laners and top laners although in some cases bot lane will take it. It mitigates enemy healing and can help secure a kill. Assassin mid laners use ignite the most frequently. Teleport is usually a top laner spell that helps you travel long distances after a short delay. Top lane sees the most use of this spell. Heal is almost exclusively a bot lane spell that heals your health bar and gives a short burst of speed. Marksmen generally take this spell. Exhaust slows an enemy's attack speed, movement speed and lowers their defenses for a short period of time. Supports will run this spell most frequently. Lastly is smite which is a required spell for a jungler to have. It is needed to last hit jungle monsters and to get rare buffs from the camps. All the other spells are niche picks.
I can tell you more but I have to step away for the moment. I will try to finish up your questions later.
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