1.有点儿意思 is right. 一点儿意思 can't express the full meaning. people always say:一点儿意思+都没有。 2. both answers are OK. small difference：the first one is a little stiff.

有点儿意思means something or somebody is quite interesting . E.g 你这人有点儿意思。 这个地方有点儿意思。 Never heard“一点儿意思”， but its common to say “一点儿意思都没有”，means its not interesting at all。 in other case, when you give someone some gift, its humble to say “这是一点儿小小的意思。”means, its just a little gift which isnt worth that much. 不习惯，means you are not used to it. 还不习惯，means you are trying to get used to it, but seems it takes time.

有点儿意思or有一点儿意思 还不习惯or还没习惯