Am I expected to bring a poster presentation to the conference? Or is it typical to only give a talk (with a powerpoint, etc)?
It depends on the form of your presentation of your paper and the conference rules. I won't say that it applies for all conferences, but as far as I know (and was involved):
- If you have oral presentation you are supposed to have you slides with you in form of
.pps or any other form defined in conference rules. Sometimes you are expected/allowed to use your own laptop. Sometimes you are allowed to use only the PC provided by the organisers.
- If you have poster presentation you are supposed to bring your poster with you on your expenses (you = they who paid the conference fee, tickets, etc.). It is recommended to bring one "big" poster to be displayed, several A4 versions and visit cards.
You will be informed about the mandatory details when your paper will be accepted. Some conferences can be attended with flash disk, clothes and wallet only without any discomfort. When returning from some conferences you will mutter "I should have taken all the stuff with me." I strongly recommend asking someone who attended the conference before for details...
Am I expected to be at the conference the entire time, or just for my talk?
It depends on you and on the one who you represent (your advisor, your faculty, university, employer).
You are expected to be there to present your work. Some conferences maintain blacklist and whitelist of organisations based on presenters attendance on their speeches/poster sessions.
Keep in mind that conferences are there to present your work (and proof it was presented is mandatory to get funds), to know what the other groups are doing and to be in contact with them. I think second and third shall not be neglected.
You wrote It is matter of lacking money. Who is lacking the money, you personally or your faculty? If you are lacking money, don't bother - the conference fee and living cost shall be covered by your faculty - you are representing them on regular business trip. If the faculty has limitted budget they will pay you at least one whole day at the conference so try to push as much as you can out of it. For you personally, obviously.