Vissim, the simulation tool I am familiar with, provides for both right and left hand drive facilities selected as part of the development process.

Dear Joshua,

In TRB's National Cooperative Highway Research Program (NCHRP) Report 572: Roundabouts in the United States, you'll find a Summary of operational models (Table 3) in which the number of lane is specified for each method. The link is:

http://nacto.org/docs/usdg/nchrprpt572.pdf

Also, in TRB's National Cooperative Highway Research Program (NCHRP) Report 673: Roundabouts: An Informational Guide (Second Edition), you'll find the HCM method to assess capacity and Level of Service. The link is:

http://nacto.org/docs/usdg/nchrprpt672.pdf 

Regarding your first question, I agree with William Guzman about the use of Vissim given that this software allows to simulate right and left hand drive conditions without a notorious difference.

Hope you'll find this information useful for your research.

Best regards,

Lenin