I'm Chinese, but i can not understand your explanation of [倒是]. = =.... Maybe it's because i'm not a professional teacher.In spite of this, i can give you some advice.
Q1:Your answer dosen't make sense.... There is an example for you. 喜欢(倒)是喜欢,可是今天我很忙。 【倒】可以省略。 or 喜欢(倒)是喜欢,但是我不喜欢和他们一起去。
Q2: Correct.
Q3: Correct. Notice: You should use [公共交通工具]
Q4: 语法是正确的,但是我们不这么说。 Example here: 没学过,可是我可以跟讲法文的人交流。
Ps 喜欢倒是不喜欢 is not correct, you have to say 喜欢倒是喜欢 or 喜欢是喜欢。
想倒是不想:Not right. 想(倒)是想: Right.!