Regarding the RAM, remember that each display uses some so if you anticipate having two or three displays in the future you may want more than if you will only have one.
True. However, I generally take all my depreciation in the first year of ownership. I pay off my purchases immediately, and so I prefer to get the full amount of depreciation in the first year. Either way, I plan for at least 5 years of use and hope for 7.