First Build. Help Please!

This is my very first computer and mainly for gaming but i will be using it as my main computer as I will be storing Music, files etc and surfing the web. My knowledge for building computers and their parts is very minimal even after researching for weeks  

Anyways

CPU: Intel Core i5-2500K Quad Core, 6MB L3 Cache, 1MB L2 Cache, 3.30 GHz (3.70 GHz Max Turbo) 95W

CPU Cooler: Cooler Master Hyper 212

Motherboard: GIGABYTE GA-Z68X-UD3H-B3 Intel Z68

RAM: Corsair CMZ8GX3M2A1866C9 Vengeance 8GB PC15000 DDR3 RAM - 1866MHz, 2x4096MB, Non-ECC, Unbuffered

Storage: Western Digital WD10EALX Caviar Blue Hard Drive - 1TB, 3.5", SATA 6Gbps, 7200 RPM, 32MB

Video Card: ASUS HD7850-DC2-2GD5-V2 AMD Radeon HD 7850 Video Card - 2GB, GDDR5, AMD Radeon HD 7850, PCI Express 3.0, DVI, Display Port, 1x HDMI, DirectX 11

PSU: OCZ ModXStream Pro Power Supply - 600-Watt, Modular, Dual +12V Rails, SATA, 80Plus

Case: Cooler Master RC-430-KWN1 Elite 430 Mid Tower ATX Case - ATX/Micro-ATX, USB, Audio, 120mm Blue LED Fan, Black

Optical Drive: Asus DRW-24B1ST 24X Internal DVD Burner - DVD±R 24X, DVD+RW 8X, DVD-RW 6X, DVD±R (DL) 12X, DVD-RAM 12X, CD-R 48X, CD-RW 32X, SATA, 2MB, Black, OEM

Total : $1,033.85 as of www.tigerdirect.ca (And yes I am Canadian)

Questions:

- Are my parts compatible?
- Is my PSU enough to power my build?
- Can I overclock my CPU with this build. If so, how much?
- Will these parts fit my case?
- Is there anyway to boost my parts with surpassing my budget of $1250?
- Should I wait for the GTX 660 on August 16 to replace my 7850?

Any reponses would be appreciated!