"직장에서 알타님께 꽂히신듯" => 직장에서 알타님꼐 꽂히신 듯(해요). 직장에서 means "at (에서) your workplace/company (직장)". ~ㄴ 듯하다 means "it seems that ...", sometimes shortened to just ~ㄴ 듯. 꽂히다 is the passive form of 꽂다: stick something long or sharp(flag, knife, etc). In addition to "stuck, lodged", 꽂히다 is also a slang for "(romantically) fall for", "is deeply impressed/affected by". So it means, "The company seems really impressed by 알타님", where 알타 appears to be a name (님 is an honorific). That is the best I can surmise, but it could also be something else, like "(XX 씨가) 직장에서 알타님께 꽂히신 듯" (XX at work seems to have fallen for 알타님) with "XX 씨가" omitted, but it's just a wild guess.

잘 아시는 분 계신나요? - 잘 아시는 분 계시나요? or 잘 아시는 분 계세요? 엄훠엄훠(Not a formal expression) - 어머어머. This expression is used only by young women. because this expression is often used when you feel shyness because of crush.

엄훠 엄훠 is a funny, very informal, gone-too-far transformation of "어머 어머". usually, kids say it on the internet. you don't want to say it unless you want to sounds stupid. "어머 어머" is colloquial expression, meaning "oh my god". sounds girly a little. I need the context to understand the additional question.