My old vista system is feeling a little 'long in the tooth' for the gaming and photoshop work that I'm into.  I need to keep my upgrade to under $800.

Current system - to be replaced
Windows Vista home premium
Pentium Core 2 duo E5400
6 GB RAM
Multiple HDD older HDD

Things I will keep:
Computer case
PSU (650W enermax, only a 4 months old)
Radeon 7850 2GB OC

I went to my favourite local computer place today and they recommended:
CPU: Intel i5 - 4430 Haswell
Motherboard - Asus B85M-G
OS: Windows 7 home premium 64 bit
SSD: Adata 128GB (he suggested I install the OS and regularly used programmes on here)
Memory: Kingston DDR3-1600 4GB
TOTAL: $764.70 (inc GST)

So questions for the knowledgable people here:
1/ Does this look like a good price/performance balance upgrade?
2/ Should I stretch my budget to 8gb ram? If so, is dual channel RAM even worth it?
3/ What do you think of using the solid state drive for the OS and big use applications, and storing media on older hard drives? (and I could pick up a higher capacity one at a later date for photos)