To go stage 1 you don't need any mods on your car.
The brakes are more of a preferance than an essential part. Most here go for the R32/ Seat cupra or Audi brakes as they are much bigger and give better stopping power.
Though you can spend bigger money and get 4pots/6 pots, Porsche or Brembos, there are hundreds really, just depends on price/cost.
With suspension most people do it firstly for cosmetics, and secondly for handling.
You can get springs (H&R/Eibach) for about £100, they will give you about 20/30mm of drop, or you can spend a bit more and get shocks, which give a static drop and slightly better handling. Or if that isn't what you want then there are coilovers, which you can use to adjust the height, and ride. Or lastly there are coilovers with dampeners in which means that you can adjust the harshness of the ride, on track can have it very firm, or on the roads as soft as you like.
Hope this helps.
(and don't worry about the questions, most here are more than happy to help and advise.)