yea welcome to PhantomPilots but I'm not sure you're in the right sub-forum.. this is for the H3-3D gimbal specifically.
so it sounds like you already understand the difference between the Vision and non-Vision Phantom 2 lines and you're going with the non-Vision because you want to run your own GoPro. Some good news, you won't have to do any soldering that's an old video and now there's a pre-made plug and play cable.
So you'll need to buy a Phantom 2 with H3-3D bundle. Combined with your own GoPro, that gets you up in the air recording cool videos. HOWEVER you have no mechanism for seeing live through the eye of the gopro to line up your shots at all. For that, you need to add what we call a FPV system to transmit live video signal from the Phantom down to your receiver on the ground. Specifically you'll want FPV in the 5.8Ghz range so that it does not interfere with your 2.4Ghz remote control of the Phantom (this is the same reason you don't want to fly with the gopro's wifi enabled.. 2.4ghz) Think of it like your own little private short range TV station.
an iOSD Mini is a device which sits in-between the video signal coming from the gimbal/Phantom and the transmitter. it overlays live telemetry data onto the FPV video feed (that you see on the ground) to provide a bunch of useful info such as compass, battery level, GPS satellites locked, distance from home point, speed, etc. you can have FPV without an iOSD, but for the extra $70 you really should just get one, especially considering it's plug and play now.
If you go with the ImmersionRC 600mW transmitter (which you should),
here is a pre-made, plug and play cable for connecting the IRC transmitter & iOSD mini to the Phantom mainboard. The function of the ImmersionRC transmitter is (hopefully) obviously the device which actually transmits the video signal from the Phantom.
Note: you will indeed want to perform the "internal iOSD mini install" that is described in the first 2 minutes of the video you linked. move the connector up inside the body and now all your connections are nice and tidy up in the Phantom body.
now on the ground you need a way to receive that video signal right? There are a few LCD displays with a 5.8Ghz video receiver in them which can natively receive the video signal that the Phantom/IRC600mW is now transmitting. There's a 7 channel Black Pearl display (you do NOT want the 32 channel BP), or a Boscam/Neewer RX-LCD5802 that people say works fine. The Boscam is about $50 cheaper. Both of those displays have built in battery, but neither comes with a wall charger, so either order one when you buy or go to radio shack and buy a generic one that fits.
There are dip switches on the transmitter via which you select exactly which frequency the transmitter is using, and whatever display you get you must simply tune the display to the proper channel and voila! you're receiving the signal from the transmitter.
Now we need to talk about ANTENNAS for a second. the little stick antennas that come with the transmitter/receiver are crap you'll get very little range and they put out a linear signal pattern. You'll definitely want upgraded antennas for both the transmitter and receiver. If it's in your budget,
this 3-antenna kit from FPVLRis basically the most premium set, you want to choose the SMA-MALE option because that fits the SMA-Female connector on the ImmersionRC. You get a nice omnidirectional pinwheel for the transmitter, and 2 for the receiver: a pinwheel (shorter range, omnidirectional) and a helix (super long range, directional =must point it at the phantom). With those antennas, you should be able to get excellent FPV at any operational range of your Phantom.
To address your other issues, yes you'll probably want another Phantom battery or 2 since each one will only last about 15-18 mins, it's nice to fly a few batteries before you need to worry about going to recharge.
You'll probably also want a mount so you can mount the monitor/display to your RC. the one everybody around here likes best is this one
http://www.raveaerialvideo.com/product/ ... tor-mount/
you'll also probably want a lanyard since the RC + display can get a little heavy
"signal interference" there is a thing called an anti-interference board, it's a tiny little piece that sits in-line inbetween the H3-3D gimbal and the Phantom mainboard, and is highly recommended to install. Here is a video, you only need the first 1-2 minutes he shows how exactly to hard-mount that board to the Phantom mainboard it's very simple.
https://www.youtube.com/watch?v=1lihMnnwvQA
You may also want to pay attention to how he mounted the transmitter. you shouldn't mount it in the middle of the phantom because then you can't get to the battery release. mount it off to one side or diagonally. people often use outdoor double sided tape or 3m dual-lock. I also wrap around a ziptie just to be safe.