R vs L, pitching and hitting

Is there a BR or NERP premium/penalty they assign to players based on their hitting or pitching hand? If so would anyone care to share that info?

If "they" refers to the people who determine salary in SOM, the answer is yes, they increase the salary of switch and left-handed hitters.

I must say that I'm still a rookie in ATG, but I am pretty aware of how salary is structured in 20XX, and to my knowledge, the same logic on this topic applies to both.

As for pitchers, I'm not sure whether lefty pitchers per se have increased or decreased salary (for same quality) than righty pitchers.

What I am pretty sure about 20XX is that the salary is based on a window of lefty vs righty hitting percentage. I'm pretty sure it works this way:

1SOM determines a plausible window of lefty/righty hitting: say a window that goes from 50%/50% to 57%/43% for right-handed pitchers and 26%/74% to 33%/67% for left-handed pitchers.
2Then SOM determines the worst salary of every pitcher in that window (or more simply, the salary at the two extreme) and assigns the worst salary to the pitcher.

So an extreme 9L right-handed pitcher has his salary based on 50% left-handed hitters and an extreme 9R right-handed pitcher has his salary based on 57% left-handed percentage (these percentages may be more narrow, but it's a close approximation).

Of course, this implies that you can "beat the odds" (that is, have your extreme right-handed 9L face more than 50% of lefty hitters), in which case you have a pretty good investment.

In case you wonder where I hold this information, I have created my own rating and salary system which roughly mimics SOM salary structure in 20XX, and some of the more important discrepancies that I notice between the two systems can only be explained along the lines above. I'm still working on my own ATG system, though, so there's an unlikely possibility what I wrote here applies only to 20XX.