In CS, players more frequently use 匪(maybe short for 土匪) to refer to terrorist. 1\As I know, 土匪 is not commonly used in our daily life. Basically 土匪 is closer to bandit, which means the bad guys live in deep of mountain and live on robbing merchants who pass through mountain. To break down this word, as a adjective 土 always means vulgar, illiterate or have no fashion-sense. 匪 means bad guys(robber). Nowadays, 土匪 more commonly appears in some Chinese TV shows, whose plots refer to the robber in mountain. 2\I'm afraid we don't. The meaning of 土 confines the available scale to use this word(土匪). However, maybe we use single word 匪 more commonly to describe bad guys in video games.(especially those which contain plots about police or army) 3\To me, I will use 土匪 to describe someone really truculent, rough or rude(impolite). e.g.（someone rushes in and bothers other people）你真是个土匪。 Hope this helps clarify your question.

I don't play 反恐精英， so I couldn't answer which more normal. As for the meaning, 土匪is bandit, in daily life, we don't use it as bandit, because now days we get less and less real bandit. But we use it to describe those who are very obtrusive inoral language. e.g."你像个土匪样的 nǐ xiànɡ ɡè tǔ fěi yànɡ de “

Almost every player in china use the name 恐怖分子. Acturally 土匪 is an old-fashioned word and rarely used in daily life nowadays， But you can still see it often in TV series especially those set in old China. And it is quite different from 恐怖分子. 土匪(拼音：tǔ fěi)(英语：a bandit)，以半路抢劫、打家劫舍等为生的地方武装团伙或其成员。