Oh really? Didn't know that......That's pretty stupid. Perma banning someone is clearly abuse of power here.
It's not. After ten warnings or infractions or so, you risk getting permabanned. It doesn't happen a lot but sometimes a member breaks the rules so many times and doesn't learn from the bans that there is no other solution than permabanning the member.
As long as you follow the rules, you won't risk getting a warning, infraction or a ban. It's as simple as that.
OP: Like some already mentioned: when you get a particular amount of infractions, you get banned for a particular period of time (usually it's just a few days). Your profile will show you how long you are banned.
When the ban ends, you can just log in like any other time and continue.
You're not allowed to make a second account when you are banned (otherwise a ban would be pretty useless if you would just make accounts over and over again) but there is an exception if you think there was a mistake made and you didn't deserve the ban. You can pm a mod then who will look into the case.
But in general, other accounts if your original one is banned, are not allowed