1.
日本語学科 is a part of 外国語学部, along with 英語学科、フランス語学科、ドイツ語学科、中国語学科, for instance.
And to Japanese speaker, it is obvious that 日本語学科 is where foreign students are learning Japanese, which is a foreign language for them, as 日本語 is 国語 for native speakers as Mike san mentioned.
2.
不意を討たれて私は何も言う事を思い付かなかった。
"Taken by surprise, I couldn't think of anything to say."
て here means two things happened in succession.
First 'I' was taken by surprise, and then (or consequently) could not think of anything to say.
不意を討たれ
た私は何も言う事を思い付かなかった。
不意を討たれた modifies 私.
I, who was taken by surprise, could not think of anything to say.
3.
先 here means future, what is going to happen after the time of this conversation.
思いやられる passive, it is a set phrase.
縺翫b縺・d繧九先昴>驕」繧九代・諢丞袖 - 蝗ス隱櫁セ樊嶌 - goo霎樊嶌
おもい‐や・る〔おもひ‐〕【思い▽遣る】
[動ラ五(四)]
1 他人の身の上や心情を推し量って、同情する。また、配慮する。「被災者の生活を―・る」
2 遠く隔たっている人や物事を思う。思いをはせる。「故郷の母を―・る」「老後を―・る」
3 (「おもいやられる」の形で)悪くなりそうだと心配される。案じられる。「これからが―・られる」
4.
東京にいる者にとってはちょっとうらやましいですね。
For the people in Tokyo, (the climate in Oregon) is something they are slightly envious about.
or
For the people in Tokyo, (people living in Oregon) is something they are slightly envious about (because of having nice climate.)