[anrakushi]

ok basically for the たり structure the advice people have given hasn't been a lot of help.

you originally said:
じしょをつかったり、先生ときいたりします

first of all, your mistake here as CC mentioned is と it should be に 先生に聞いたりします. the に shows direction of the action.

when using the たり form in this way, it is used to list an in-exhaustive list of actions. What you said, in my mind, should have some context to it. for example you should start off with 授業中で学生は (during class, the student(s).....)

just for fun, show your teacher a slightly different use of たりする form by using this as an example:
田中さんは来たり来なかったりする
Mr. Tanaka doesn't always come.

as for your next question.. スウェーデン人は背が高いです is better. be careful that you use a little ェ and not a big エ