Please can i have some male and female advice? Is this guy interested in me?

Hiyaa... thank you for reading this..
Basically im 21 years old and work in a gym... A man has joined the gym about three weeks ago and i really really like him (absolutly gorg and probably out of my league).. he is 31 years old and is really nice! I have spoken to him a couple of times and seems interested in talking to me..

his mom is also a member at the gym and came upto me the other day and said "whats you name again becuz my son asked and said your a nice girl"..

i added him on facebook becuz we have some mutual friend!! (really i searched him and added him) we have sent eachother a few message and he replied back with questions at first so i could message him back but then it kind of ended with "enjoy work tomorrow.. dont work to hardxx" I didnt reply!
He asked how old i was when we were talking so may think im too young but i dont know...

just wondered really if you can give me any advice on how i should act as i really like him even though i hardly know him but would really like to get to know him... how do i talk to him without seeming to forward?
How do i get his attention?
Whats off putting and what makes a guy interested?
Im not used to dating old guys lol!
Thanks for you time.. I know it probably seems as if im reading into stuff too much
xx