Your best bet is to have a budget and then use something like
pcpartpicker to get the best of everything within that budget.
(This is the UK version but there are others)
Obviously for gfx work you need to prioritise CPU speed, RAM, GFX Card and a good solid smooth power supply.
The only advice I'd give is to start backwards and it looks like that's exactly what you've done....start with the monitor.
Your next move would be to find a GFX card that suits your needs AND that will support that monitor....no point getting a card with only display ports on it if your monitor has a DVI on the end of it....ya know?
Then you need to choose a mobo that supports that gfx card.
That will determine the CPU you can get and the RAM...how much, how fast, etc.
You also need a mobo that can support the SSD's, HDD's and possibly any optical drives you want.
You then need to decide if the stock 'air' cooling is going to be enough to shift all that heat, if not you may need to consider upgrading or even go water cooling....the 'self contained' WC units are excellent btw.
Once you have all that lot sorted you then need a good solid power supply that can handle the demand plus around 25% - 33% headroom....yes, that much! (Gfx cards can pull 200W+ on their own when pushed!)
That said, components today are more energy efficient so its common to see smaller, more efficient PSU's being used.
I think that site above gives you an estimate of power requirements based on your other choices so it makes sense to leave it till last if you use it.
That's kind of the order I'd (and have done recently) do it in although if there is a specific part you want you'll have to adapt it to suit and work around that....for instance, I wanted a specific mobo so I started there and built up from that.
In case you're worried about how much RAM you need for PS...well, PS will use what it needs.
CC 2014 has a memory leak problem and I have it had it using (for no reason whatsoever) over 25GB.
Video takes a good bite of RAM too.....I've intentionally had PS using 22GB when editing video but that really is an exception.
Normal use shouldn't use anywhere near that......just get the most you can afford, as fast as your mobo will support and with as little latency as possible.
Regards.
MrTom.
