Risk is the classic game of world domination. It has been around for decades and is still played religiously today. It is a combat strategy game boiled down to one very pure mechanic. There are many maps and versions but in the original, the game board is a map of the world broken up into many territories. You add territories to several to start and the entire game is you both protecting what you have and taking more. This is done via a showdown over dice. That is it. This makes for a very focused winner take all play. It is a long game, but it is incredibly satisfying and keeps you entertained from start to finish. This is everything you could want to know about Risk board game.
Risk was designed by Albert Lamorisse and Michael I. Levin. Lamorisse was interestingly a very important french filmmaker who at one point won an oscar for one of his screenplays, Le Ballon Rouge (1956). Risk was a side pursuit and then sold to Parker Brothers.
Some Themed Versions of Risk: Star Wars, Lord of the Rings, Narnia, Transformers, Halo, Metal Gear Solid, Starcraft, Walking Dead, Plants vs Zombies, Doctor Who, Marvel Cinematic Universe, Star Trek, Rick & Morty, Vikings, Assassins Creed, Elder Scrolls and Game of Thrones.
Either. Those are two different modes of starting. Each one has its pros and cons, it's up to you.
No. You always need at least one soldier to stay back and one to attack with. This means your minimum to attack is two soldiers.
If you defeat someone and go over five cards doing it, you need to turn in a set immediately and then place those troops. This is normal and usually part of the wave of someone's final big stand. If you get cards but it puts you at five below, you just get the cards, no further action required.
No. That is why the cannons and horses exist, once a territory starts to get crowded you can consolidate.
That is impossible. Given the math that there are three types and you need one of each or one of all, there is no mathematical combination that would not allow you to have a set at five cards.