Above the very lowest leagues, most players are very polite. They are also very terse. Some common abbreviations are used in chat for a friendly (though fiercely competitive) match.
The following expressions are often used at the beginning of a match.
- gl: "Good Luck"
- hf: "Have Fun"
The following expressions are often used at the conclusion of a match.
- gg: "Good Game". This is the usual way to concede defeat.
*Assuming that you're playing as a protoss.
The expansion is dependent on the map and the opponent you face.
Against zerg on a large map like Shakrus Plateau, the 1 pylon, nexus expand is viable (unless they go 6 pool), because it's almost guaranteed that the zerg will expand as well. It's also because it's a long travel time for them, and a small ramp, they will usually also have a cannon or two to help protect against high aggression for this build because as you put it, they will have a smaller army.
To answer your questions:
1. See above. It is really map dependant, you wouldn't do a 'no-army' expand on a map like Xel'Naga Caverns against terran.
2a) In a PvP it's generally a bad idea to go this build, a 4 gate will crush you like no tomorrow. I normally see this type of build almost exclusively in PvZ. Because of proper scouting they will either respond with their own expansion and you're in for a long term game, or they will apply quick pressure.
2b) Not really sure what the question is, are you asking how to prevent other races from scouting your base as protoss against this build? If so, you really can't, the amount of time required to get a wall to stop a scout is too long. On one base play, normally you chronoboost a stalker to stop the scouting probe/scv/drone, but if you are going for this fast expand, you can't do it. They will see that you are going this build.
3) I don't understand this question.
Best Answer
There are no new pure detector units in Heart of the Swarm.
However, the Protoss Oracle can temporarily gain the ability to detect via its "Envision" ability (this lasts 60 seconds, and costs only 50 energy).
The main thing to watch out for, then, is that a protoss opponent without a robotics facility can still field detectors if they have a stargate.