1) You can trigger your job by following code (you need to obtain job Id for that - see point 2):

ScheduledJob jobInstance;
if (job.InstanceId != Guid.Empty)
{
    jobInstance = ScheduledJob.Load(job.InstanceId);
}
else
{
    jobInstance = new ScheduledJob
                      {
                              IntervalType = ScheduledIntervalType.Days,
                              IsEnabled = false,
                              Name = job.Name,
                              MethodName = "Execute",
                              TypeName = job.TypeName,
                              AssemblyName = job.AssemblyName,
                              IsStaticMethod = true
                      };

    if (jobInstance.NextExecution == DateTime.MinValue)
    {
        jobInstance.NextExecution = DateTime.Today;
    }

    jobInstance.Save();
}

if (jobInstance != null)
{
    jobInstance.ExecuteManually();
}

2) For checking whether job is running - you have to get job Id somehow.

var isRunning = EPiServer.DataAbstraction.ScheduledJob.IsJobRunning(job.ID);

To get job id you need to know type and probably assembly as well (to avoid collisions):

var job = ScheduledJob.List().FirstOrDefault(j => j.TypeName == typeof(YourJobTypeName) && j.AssemblyName == "YourAssemblyName");

You have to create new ScheduledJob instances for `jobs` (or actually `plugins`) that has not been executed yet - therefore -> there is no job instance generated for those ones.

You can check some sample code here: https://github.com/valdisiljuconoks/TechFellow.ScheduledJobOverview