Asking out a Co-Worker

Please try to read everything so you get a realistic picture. Appreciate it!

Trying to keep it short. Met a girl at my work that is quitting soon. She seems to show signs she likes me (always going out of her way to say bye to me when usually nobody does that kind of thing, always laughing at everything i say and smiling directly at me. again could just be courteous and friendly things but you never know) and I know I really like her.

1. I don't know a whole lot about her but going to ask her out one night when she's heading out of work. I can't talk to her or ask her these things during work because the place is small and other workers/boss will overhear us. I was going to slip her a note with my number on it but not sure or message her on social media but that's kinda wishy washy i think,
So I decided a good choice might be to go back to work a night she's getting off late and ask her when she's leaving the building one night? Would that be weird because i thought it would be cool?

2. she's 29 years old and i'm 23. Any problems with that?

3. Not completely sure about her distance. She's quitting the job and not sure where she's going in a month or so. Overhearing her, and what her facebook says, she used to live 2 hours away, and this summer (idk if it's temporary) lives very close to me so not 100% sure. If she's 2 hours away can you make something work if worse comes to worst?

Thanks guys.