"What are your interests?", or "What are your hobbies?" 'to be into [something]' means to have an interest in something. 'by the way' is maybe just like '講起又講'? It just means to mention something in passing, but it's used a lot in English. It's a very casual saying. Some examples: "I used to like The Beatles, but I've been really into the Stones lately" "Do you like this movie?" "Eh, I'm not into Sci-fi movies in general" "I used to be very lazy, but lately I've got into exercising"

顺便问一下，你的爱好是什么

by the way 译为顺便一说，一般和句子其他内容以逗号分开。 句子改为：What are you into , by the way? what are you into 译为你喜欢什么。 最近有一部美国电影 He is not that into you和此句类似 。 that into 可译为那么喜欢。