a) Are you sure you shouldn't be passing a SequenceFileViewMgr instead on an ExecutionViewMgr? Typically, process model entry points apply to files, not executions, thus you probably have no entry points for your ExecutionViewMgr and therefore get the index out of range error when trying to access one.
b) If you really want to use entry points that can apply to executions but you don't always have them available, you can check if an entry point is available before getting a command to execute it. To do this, use code like the following:
int numInserted;
this.axApplicationMgr.NewCommands().InsertKind(CommandKinds.CommandKind_ExecutionEntryPoints_Set, this.axExecutionViewMgr, -1, "", "", out numInserted);
if (numInserted > 0)
{
// entry points exist, use them here
}