Keep on deferring questions to a higher-up/someone else. It might not work in all cases, but keep it up. "(Fill in the blank) might know, why don't you try asking them?)" Or "the information you need is in the document I provided." Tailor these to your needs for as long as you can. You're the newbie there, you can do this under the guise of finding these things out yourself.

I had to keep up this tactic for a while with someone I work with before they got with it, but it should work. Keep a professional tone, but don't be overly polite. These people prey on our desire to be nice, but a strictly professional demeanor with them can shut this behavior down. If they try to have a conversation about anything other than work-related topics, say something along the lines of "I'm busy working on (whatever you're doing/made up task) please excuse me." Don't add anything out of politeness like "we can talk later" or "not right now" or "I'd love to chat, but..." Don't open the door for any future possibility of conversation. Work in the grey area of professionalism, not being nice or rude. They can think you're a bitch all they want, but there's nothing they can do about it.

Find novel ways of excusing yourself from these situations. Hopefully they'll take the hint sometime. You've replied to someone else about it being annoying to always have to excuse yourself, but it's much better than the alternative.