Let me do some poking around. I was researching this a long time ago when I was buying parts to build my M17xR2. This much I can tell you for right now.
The best CPU for your rig depends on the motherboard you have. The R1 has the F415N motherboard. It supports i5 processors, which are dual-core, while the R2 has the 14M8C motherboard, which supports i7 quad-core processors. 8GB is the maximum for memory, not sure about the video, but I do recall something about a dual-card setup requiring more power. If you don't already have a 240W adapter, consider investing in one.
And since your system will be running hot, be sure to invest in a decent laptop cooler. Cooler Master has some good ones. This one, for instance, is cheap and has a HUGE fan in it:
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Doing some research, found that the R1 can supposedly support some quad CPUs...looking to verify. But first things first...which system do you have? The easiest way to find out is to look at the bottom of the base for the Intel sticker. Blue is i5, black is i7.