How do i know if he is interested in me ?

There's this guy in my office, who i get along very well. I am suspecting he is interested in me, but i am not very sure.
Details:
1) We were in IT shop and he actually get the membership which cost small amount. And told me to use the membership if i want to do so, it's ok. But looking at it, he didn't buy anything from there. But me.
2) he will come to my work area chat with other guys, but there are times when i turn n look at him. He is there looking at me. But then look away.
3) He ask if i am interested to go KTV ? which end up we went with office guys.
4) We both want 2apply for Car-sharing program membership. which he plan to get it next mth. And he teasing me to join as sub-member of his. When i told he i cn't coz we are not related. He tease to say you can haaa..
5) suddenly out of no where, he tease me by asking if i want to rent his house room. which i never mention of moving out ?? But in my heart i am looking for room
How ?

He ask if i like ktv before company event. So by chance last month after company dinner, the office group of guys plan to go so everyone go together. As for gender, i am a girl :)

He is too scared of rejection. Your icon looks male. If you are male and so is he, he may be afraid of people finding out. He might be acting like he is kidding, when in reality he means it

Sounds like he's playing you and you are falling for it.

sounds like he is into you I think you should ask him if you like him then do something about it but be-wear relationships at work could be fatal

Is a sign of this guy is very interested in you. Then, the renting of a room from him, you can put this like a joke and see how he's react. Like how much he's going to charge you, observe his body language of asking him whether can bring any man( friend) back (just visit only ) ? Thus ! observe him carefully on these questions.

sounds like hes interested in u, its obvious! ask him then get em drunk and do him its what every guy want unless hes gay or a little *****! use condoms

He may just like you as a friend.
I would not read anymore into it other than he is being nice.
I do not think guys love all girls.I think they like to talk to other genders.
I think if he was not just being friends with you. He would have not taken his friends with you two to KTV.