If I bought a new iPhone from ebay, is there a way I could still have the same contract?

So, i have had my iPhone for a few months now. I was in my hot tub with my friends and i was listening to music.. i was going to try and text my mom back and it slipped out of my hands and fell into my hot tub. It was only in water for a second because i freaked out and grabbed it out as fast as i could. A few months before this I had dropped my phone and cracked the screen and so i have a huge hole in the upper left hand corner.. so of course there is going to be extra water in the phone. I immediately got out of the hot tub and put my phone is rice. I left it in there for two days... and today I went to use it and it was perfectly fine.. until i tried playing music.. The speakers don't work! I can only listen to something with headphones in. ALSO there is a piece of rice stuck.. i mean REALLY stuck in the area where the charger is supposed to plug in. It still charges but i can tell something is bent.. I am probably going to get a new iPhone from ebay.. but i can't afford getting a new contract right now. Is there a sim card i can put in the new iphone? Could i just put my sim card in the new iphone and i would still have everything i had on the last one? Please tell me! I need help!