3. How do you say this:

" I have studied Chinese for many years , but it has been on and off"

我 已经 学习 中文 X 许多 年 了， 但是 X X X 断断续续 的 .

and this: "

I have studied Chinese since college but I have spent months

我 已经 学习 中文 从...开始 大学 但 我 已经 花费（用） 几个月

===》我从大学开始用了几个月学习中文

maybe years without studying Chinese".

大概 几年 没有 学习 中文 了“ ===》大概几年没有学了

I would appreciate it a lot if you could give me some grammar points on these two.

4.-I would like to know how to say "I went to that school" "I went to college" and "I graduated from the University and I studied -major-"

went XXX-ed = 以前 ，做过...(done something)

"I went to that school"

我去过那个学校

"I went to college"

我去过那个大学

"I graduated from the University and I studied -major-"

我毕业 于 那个大学 而且 我 主修 。。。。。

Questions:
1. In Chinese, is it ok to use the expression "my country" as 我的国家? I have always been unsure about this because I am afraid it will sound like I actually own the country :p

   my country = 我的国家

2. "they teach English and Chinese at   the school" but I have no idea how to say this.

              教      英文     和   中文      在   这个学校  ==>这个学校有教中文和英文

1、Yes, it is ok to use "我的国家"，the meaning of "我的国家" equals "my country" in English.

For example，You can say "This is my country"="这是我的国家。"

But when you say "America/Japan/China.....is my country", you'd better say"美国/日本/中国...是我的祖国"or“我是美国人/日本人/中国人...”
2. 他们在学校教英语和中文。

3.我学了很多年中文，但是断断续续的。or 我断断续续地学了很多年中文。

我从上大学时就开始学中文，但是到现在为止已经有很长一段时间没有学了。

4.I went to that school=我去的那所学校

"I went to college" = 我上大学，but it doesn't seem to be a whole sentence, you'd better add time or place to the sentence, for example，我在美国上的大学。

5.我大学毕业，学的是...专业。

Thank you very much guys!

just one question Alan,

you wrote:

但是　ｘ　　断断续续的

What do I　ｉｎｓｅｒｔ　ｔｈｅｒｅ?　Ｏｒ　ｉｓ　ｔｈａｔ　ａ　ｐａｕｓｅ?

it's more common to say "(在)我们国家" or you say your country's name.

to the second one, we say "这个学校同时教授英语和汉语".

to the third, 我已经学汉语很多年了,但只是断断续续地学. 大学时,我就开始学习中文了,但是最近很长时间都没有继续学了.

4. 我在那所学校学习.

  我上大学.

我毕业于university大学,专业是major