Since it has an option for AA battery, I don't need phantom power right? Do absolutely need an audio interface? or can I just use an XLR to 3.5mm cable and connect it to my computer? Are there any other things I need to look at to get decent audio? I'm really confused and haven't really found a straight forward answer online, really sorry for being dumb and thanks a lot for your help.
Never forget that no matter how much you spend, distance is everything. If you want the best results you'll want to boom your shotgun right above or below the person. Camera mounting will gives you the worst results because you will always be further away than you can get it with a boom. I would rather use a $50 mic boomed (or lapel) than a $2,000 mic camera mounted any day.
Sounds like you want to use this mic as an input to your computer? This might not be the right mic for that purpose - it's a balanced, mic level signal, designed to go to a balanced mono input on a camera or mixing desk. Something like the RODE NT-USB mic is probably more suited to your purpose.
To input the NTG2 (mono, balanced) mic to a 3.5mm TRS (stereo, unbalanced) on your PC, you'd need a converter cable: https://www.swamp.net.au/xlrf-to-3.5mm-trs-balanced-to-stereo-cable-mic-to-camera-cable
Lots of people make these, but that's what you need. If you use a straight through cable that just converts the connectors, the balanced mono audio signal will cancel itself out going into stereo, and you'll hear nothing on the input. Also, most PC inputs are line level, so the mic signal will be much LOWER (mic level), which may also impact your ability to get the volume you want out of it. See also: https://sound.stackexchange.com/questions/27539/difference-between-microphone-and-line-in-inputs
The mic is also ideally designed to be powered by the device using it (video camera, etc), the AA battery will work fine to power it, just be aware that they go flat without warning, so make sure you're monitoring what you are recording - that mic otherwise has no indicators to help you. Also be sure to remove the battery if not using the mic for an extended period, so it doesn't leak inside the mic.