Upgrading store-bought HP Envy 700-230

[DK5050]

Hello. I bought this Hp Envy 700-230 and now I want to upgrade it for better gaming power.
Here's a spec sheet: http://store.hp.com/wcsstore/hpusstore/pdf/f3d88aa.pdf

This is my first time upgrading. I have a lot of questions but know that I need a better graphics card and power supply. Right now it has an Intel HD Graphics 4600 and 300W Power Supply.

Could anyone please help me understand:
1. Are most graphics cards the same size? I want a powerful Nvidia card because they are the most supported.

2. My current card has DVI output, not HDMI. If I install a new graphics card with multiple outputs including HDMI, do I need to cut out new holes in the back of my case to make room?

3. Are all PSU's interchangable basically? I need a better PSU that fits inside the case (600 W should be OK).

4. Is my current Motherboard OK? I have no idea because I cant' find It's Intel's own "Pegatron Memphis-B 2AF7" link: http://support.hp.com/za-en/document/c03924124

5. I believe my CPU (i5-4440) is sufficient, yes?

6. Should I get a new fan as well?


Thanks for the support!

 

[popatim]

1: No though most are sized to fit most cases.
2: No, it will go into a slot and require you to remove one of the slot covers on the rear of the pc.
3: HP currently uses mostly standard Power Supply Units in their normal sized desktops and yes you need a bigger PSU.
4: Its made for HP by Pegatron. Its not great but will work plus its what your OEM version of windows is tied to. If you replace the motherbd you get to buy windows again.
5: yes
6: is there an empty fan slot then yes.