First time snake owner, looking for help!

[Kylie]

She hissed at me once when i was taking her out of her tank, and once when i first got her and was just randomly holding her, i think that's the only 2 times she hissed at me, but she hissed at my mom and friend alot more in a short period. That probably means that she didnt feel to comfortable? I have a cat and she likes to sit up at the tank and stare, sometimes pill lightly paw at the tank, will this stress bella out? When i get my new used tank, what should i use to clean it out? or disinfect it per say. Any certain type or brand of thermostat and uth i should use? can i stick with my lamp? or would that be a bad choice? Anything elce i should order online? is ebay a bad site to get some things off?