I am looking to upgrade my Mac for making music with DP8 and some sample libraries. Any advice would be greatly appreciated.

I have the following MacBook Pro: 15" Retina, Late 2013, 2 GHz, Intel Core i7, 256 GB Flash Storage, 8 GB RAM.
1. ) Is a flash storage drive the same thing as an SSD drive? If not, can I have someone put an SSD drive in to replace the flash storage? If so, how big of a drive can be put in?
2.) Is the RAM upgradable?
3.) Any other suggestions to speed my Mac up?
Many thanks.
