How to execute same set of test cases or test suite with different roles

Another option, though may be considered a stretch for correct usage and would be affected by how you currently use Test Environments, would be set up a new Environment Type, Business Roles, under Manage Project Properties->Lab Resource Properties. The Test Plan could define this a Platform (under the Test Environment section). Execution Records could be generated for each role through the Environment. The environment is a column of the Execution Records table and the Results table.

Have you looked into using Test Script Test Data? You can configure a test data file to contain, per row, a business role. The script can reference test data column values (e.g. business role name). The script will repeat for each row of the test data file.

Yes. It's possible. You can create two test plans for the same test suite. Then assign the two test plans to two execution records. By the way, at least one of Test Suite, Test Environment, Test Plan and Test Milestone must be different for each execution records.