Hello, i have started AS politics this year, and i can say from personal experience that 1)it definitely was not what i was expecting, but i enjoy it none the less, 2) it is essay based, so you dont get short answer questions (at least not with Edexcel, idk about other exam boards but i think the same applies), 3)wide range of things in all honestly as its a good range of skills, others will likely be able to answer this better than I, 4) politics isnt hard as such, you just need to have good essay writing skills, and yes, you need to be good at forming arguments, as you will need to evaluate things, and often use counter arguments, and im not sure about the last point
It is slightly hard to get your head around if you dont have any prior knowledge, but if your teacher is good, they will start at the very very beginning so everyone is on the same page