The added stress from 1x SSD and 2x RAM sticks is negligible. Unless the PSU is already at the absolute max, you don't have to worry. I doubt that is the case here.
RAM is one of those things you never realize the value of unless you have a problem. If you ever experienced thrashing in the past, you would know how nice it is not to experience it commonly.
Just take my word for it that 8 GB total is a really good number for 64 bit OSs.
It really matters more what you do with it for how much benefit you will see out of it, but 4 GBs is pretty slim going into 2012.
I am getting my other 4 soon too for that reason. I just recently got 7 (before I had XP 32) and the extra 4GBs was one of the main things I was happy about in the change over.
Crucial SSD - Probably fine. No clearly superior SSD maker has yet emerged so just get one that makes sense price and space wise without worrying too much about the brand for now.
Yes I do some video editing and work with big files so I think I will benefit from those extra 4GB.
My research on SSD's has shown the Crucial SSD's to have the best reliability and I like the price of it to.
So ye, thanks for your answer!