You have the simple right answers to your questions at the end of your letter but pretending not noticing them.
Do not use only your feelings and imagination to determine things. Examine your feelings, as they may only be admiration, since you were not sure of them until this moment.
You needed not to do any trick to add somebody you know from work to your Facebook while you knew that network very much and knew you can add people you knew as friends. However, that mistake is not a big problem. People even add others they would like to befriend them.
Follow the simple logic in any new love relation that starts by knowing the other person. It is not bad to know personal information about him to help you solve your love problem, before expressing that feeling to him.
There are some easy ways to know personal information about anybody these days, forget about that person being a special one. You can ask him in directly about the most important people in his life and his friends providing that you start speaking about the important people in your life and your friends.
Ask him of his opinions about the friendship relations between women and men for example and then go from there to see if he has friends from the gentle sex.
Just look around in your work environment. People sometimes speak about this person and that. You will know some information about him from their speeches. You can also encourage him to talk about personal things by starting talking about yourself sometimes.
Friends actually talk about many things and love is among those things.
While talking with him you can talk about some stories of love you read in your local newspaper or seen on TV channels and then mention your point of view on that topic. He will probably start talking about it too and from here, you will know more about his thoughts, feelings and character.