What kinda questions can I ask to know her more through text?
You can't get to know someone through texts. Anyway if you already know her well enough to have her phone number and are texting her regularly then do what Dominic says and just ask her out for God's sake and get to know her in the normal way. Also, it's true that her being Polish is irrelevant in terms of whether she wants to have a relationship. Some single mothers with a young child don't want a guy in their life and some do. Nationality doesn't really have any bearing on that. As for Polish women in general, when it comes to 'dating new guys' they are not at all shy. However be warned that once they decide to get involved with you they expect a lot of committment quite quickly. They expect the relationship to go somewhere - and fast, by 'western' standards.
To be honest though, you sound a bit too immature to be considering a relationship with a woman who has a kid. Just don't start anything if you're not ready to fill the role of step-father at this point in your life.