I'm looking to build a PC within the next year for gaming, video editing and possibly streaming. My budget is ~$1000 for the actual PC, and ~$600 for the monitor, keyboard, mouse and headphones. Where do I start?

Built my own PC last year and found that PC Part Picker was the biggest help, probably good idea to start for the PC.

+1 for PC Part Picker. Spend some time looking through the build threads on there and get an idea of what you can get for your money. When I built mine a couple years ago I kept a spreadsheet of parts regarding specs and price and I just fiddled around until I found the best compromise. 

Linus Tech Tips is also a good Youtube channel, he even has full step-by-step PC builds (highly recommend watching these if you plan on putting it together yourself and you're a first timer) as well as part reviews and comparison tests but that's more for newer/more cutting edge stuff really. 

Prioritise the CPU and make sure you get a dedicated graphics unit (GPU) if you want good gaming, the built in stuff that comes with motherboards is pretty limited. You can save money on the motherboard and power supply if you take your time and make sure you get one that suits your needs without having a bunch of ports or other features you'll never use, or in the case of the power supply, buying one that is complete overkill. Once you have a couple of the parts decided on, you can use online calculators to help you work out how powerful of a supply you need so this part can wait until later in the selection process. 

If you need a hand with anything else feel free to PM or just keep this thread updated. 

As far as everything else goes, that just depends on what you want to prioritise - screens come in all different shapes, sizes, and types of construction (e.g. TN vs IPS if you're interested in looking it up), so I would go check some out in person if possible. I have a BenQ currently and highly recommend it, but the screen alone was $550 when I bought it so it all depends on what you deem reasonable. 

Gaming mice are pretty cheap and cheerful these days, $50-$60 should be plenty. Mechanical keyboards are also handy for their feel, durability, reliability, and responsiveness. If you're not so fussed about how it looks then go for a Ducky or something similar, no frills but solid and dependable. Logitech make cool looking stuff but to be honest a large number of the keys on my G710 are broken after 3 years of use and replacements are pricey (and I already had one set replaced under warranty).

Built mine this year after months of slowly waiting for sales and then buying piece by piece. The accessories are actually the cheapest and easiest to source. You want to go out of your way to source a good CPU so get that and a motherboard first. Also you don't need to go nuts on a new GPU if it's your first time. Even the most basic Graphics Card will outperform your console comfortably so enjoy the upgrade for now, get a feel for how it's performing and then you can decide on what new GPU you need to meet your specific requirements.

My main problem though was that I was cheap with my case and bought one that technically fit everything but was too tightly packed that I couldn't put it back together without ramming things in.

When it comes to editing/gaming/streaming lumped in as one kinda requirement (and at that price point no less), it will really depend on what games you're gonna attempt to be playing.

-PB

Also don't go buying anything within the next month or so, new gear is about to drop and that may greatly affect the landscape in terms of pricing/performance.

-PB

If it can play BF1 on just about max settings I'm all sweet.

Well comps can, but depending on the resolution you want, you won't get that for 1k.

-PB

1080p should be fine.

BF max @ 1080p will be hard @ 1k ahha

-PB

How much should I set aside for the PC + peripherals?

Just worked out the budget for my PC.

$1300 for the actual PC and almost $1000 for Windows 10 and all the peripherals (monitor, keyboard, mouse, etc.).

That is black market organ selling territory.

lol not really, just what a decent PC costs.

I for many years always built using top tier shit, most comps were 4-5k

You're very lucky that you're coming into an era where you don't need to spend that kinda dosh to get the absolute best performance for what you want to do now.

-PB

Not sure how you're ending up at 1k for peripherals. 

$250-300 for a good monitor. 
$100 for a decent mechanical keyboard.
$60 tops for a good mouse. 

Upgrade monitor later down the line in a year or so when you can afford a graphics card that would take advantage of 144hz. 

I've got $153 for Windows 10, $400 for a monitor, $185 for a keyboard, $85 for a mouse, $69.30 for a headset and $65 for speakers because why not this shit's already costing an arm and a leg.

What monitor are you chasing?

-PB

Asus VG248QE.

Yeah you don't need a 144hz monitor if you won't be able to get near those frames. 

Just get a standard 1080p gaming monitor (Benq are great) and spend the left over on an SSD. 

Exactly what I was going to say lol.

If you want 1080p, max settings AND 144hz then you're gonna need min 2k on the PC, half of that will be the graphics card alone.

Need to downscale fam.

-PB

You can buy an ultra wide monitor for the same price, video editing would be great for that, gaming also but you will have a less refresh rate. But unless you think you will be some super pro in first person online shooters i would not worry about 144 hz anyway. 

Is 4k streaming worth it and can NBN handle it?

Depends if you have the hardware to watch it (TV/monitor).

My mate has 4K Netflix on 100/40 NBN and it's just fine.

-PB