((Yeah, this is my first Realpolitik game, too.
And I . . . realise I don't actually know what IAAR stands for.
I'm sure the Grand Majah can explain better than I can, but here are some of my initial thoughts.
City-wise, maybe hold off until you've caught up and decided what party you want to join (if any --- presumably you will, though, but independent candidates can run) before firming up on which city you want to reside in. Because if you change your mind later, you'll usually have to pay relocation costs.
On the roleplaying question, I think you can be as light on or as hardcore as you want.
From a game mechanics point of view, you are one player (the spreadsheet of influence only tracks to whatever you do). But to use me as an example, everything I do as an elected representative (formerly candidate) tracks to "Melda", but I've created my main player character "William Melda", who will eventually retire and die and be replaced by his son "Charles Melda" (all "Melda" according to the NPC voters who don't differentiate) --- oh, and each in-game
Civ turn is one year on the calendar, which is how I can age my character realistically. However, separate to me I've also created a non-partisan newspaper (just read some of my interviews with the political reporter Harland Godwin, where he/me grills me pretty harshly) called the
Haven Herald, and three reporters (political, cultural and general) to staff it. But all these NPCs don't, as far as I'm aware, count toward voting intention for anyone, it's just a layer of roleplaying for extra enjoyment and immersion --- as well as a platform for players to broadcast their views or get called out on things.
As a private citizen of Pulias, you are fairly limited as to the impact you can have on the game. But you're not invisible. You can either make public statements extolling the virtues of certain actions, or try to sway the elected representatives to undertake such actions. You can write to your local representatives --- if you reside in Haven of Peace your two Senators are the Prime Minister, Senator the Honourable Heerlo and myself, the Acting (usually Deputy) Prime Minister, Senator the Honourable William Melda. Another way you can have an impact is to join a political party. Since I'm writing out of character I can be dispassionate about this (which I couldn't be in-character), but the three parties are fairly equally matched in Senate representation and influence separately (you can access all election summaries via my signature, but the most recent elections results
can be found here). I believe each party has its own party room (i.e. social group on the forum for private discussion) where you can seek to influence policy development ('I think we should do this').
If you join the Pulias People's Party (my party) or the Pulian Advancement Union you will join one of the two parties fortunate enough to find themselves forming a Coalition Government at this stage. If you join the Pulian Imperial Party you will join the party currently in the role of Official Opposition (whose role it is to hold the government of the day to account for their actions and promises). In ten years (in-game
Civ turns) the Senate will be dissolved and a general election held. If you join a party and get their endorsement to run as a candidate you could win a seat in the Senate and become a Senator. Then you could potentially be a minister in the next Government, or could be a member of the next Opposition.
At the moment the current Government has issued its orders for the next few turns, and the Grand Majah is in the process of giving them royal assent --- i.e. he's about to play through the next few turns until something comes up that needs the Government's, or the Senate's, attention.
So hopefully that clears up / answers your questions for now.
If not, let me know and I'll try again.

))