Hey, I do Edexcel Politics right now and I love it!
1) I do recommend it, it's super interesting especially when you do different ideologies.
2) I find that it links well to History because in all of my history units we look at the politics of the nation we're studying. Also links to economics and geography because some of the topics overlap (things on globalisation, IMF etc.) Also it's just great for your general knowledge ngl.
3) Well for Edexcel there's 3 papers and the first 2 have 3 essays (30 marks, 30 marks and 24 marks). The third paper I'm ngl idk how it's structured because we've only just started it. Good thing about the essays though is you always get a choice from 2 questions (at least for papers 1 and 2) and they're quite easy to structure (in comparison to history essays for example).