1.（1) When you use" 和“, you can abbreviate some introdutory words. For instance, this is my dad, this is my mom, this is me and （和） our dog. It's more natural to omit " 这是” before " 我们狗“ --这是我和我们的狗。Otherwise, if you don't feel like omitting anything, you can introduce by telling the listeners " ...这是我，这是我们的狗。” （2）When you describe something that belongs to somebody, you should use " 的“ to link the owner and the belonging. The owner goes first, then " 的” , and the belonging is behind " 的”. --我们（owner)的狗(belonging). "的“ is kind of like the ('s) in English 2. By 店家公司，do you mean buisiness company? If so, I guess you are looking for " 商业公司” or " 商务公司“. " 店家 is more of a commercial body of quite small scale or can be referred to as the owner of it sometimes. 3. Now in Chinese, the employee of a decent company is called " 职员（client）” more often instead of 工人. But it's understandable to use 工人 in this case. 4. The Chinese word for student is 学生--...他是学生 5.You only use " 也“, when you describe something that is the same or very similar with the former stating. Because your brother is not studying in the certain university as you are, you can't say that you are " also(也）" studying Chinese and English in the *** university. --我在贝加莫大学学习汉语和英文。 6. I have a pekinese--我有只狮子狗。“只” is a measure word that can be used on dogs. You can say 我有只狮子狗 or 我有一（one )只狮子狗. They are both ok." 一(one)" can be omitted here.

长 is chang( 2nd tone) and 还 is hai(2nd tone) in this sentence. In this case, 长（chang) means the period of time is long, as an adjective, while 还 （hai) is an adverb with the meaning of " still".

得in this sentence should be pronounced as de（in a light tone), and 着 is zhao( the 2nd tone). Normally, 得 is pronounced as de, well, if it sounds like dei, then it either goes with "劲儿“ as " 得劲儿” which means feeling comfortable, or is before the adverb with the similar usage of "should" in English

下雪. 你喜欢雪?

今天这里在下雪! or这里今天在下雪

这里不经常下雪。