Questions about Virtual Races

Is there a guide anywhere on how to do a virtual race? 

I have seen a half dozen virtual duathlons pop up and none of them have any information on how to do their race. 

One race only will allow indoor cycling.  How do you know when you have finished your 20K or 40K if the only metrics you see on your bike trainer ap is Watts? 

If you are going to do a warm-up before the bike segment on your virtual race do you need to stop your session and load a new one to start the virtual race?

If you are doing the whole race continuously do you need to hit the lap button at the start of each segment or change the mode from run to bike back to run or can you just race straight through without worrying about modes, transitions, etc?  

If you have access to a track and are able to measure the exact distance of your run but your GPS-enable devise draws a straight line to calculate distance every time its reception gets blocked and your track is curved to where you complete the exact distance of your race but your GSP says you still have 0.21 to go will your run get scored? 

Can you upload a specific segment to that segment of your virtual race? All they ask for if you register for these races is for your fitness account to be synced to their website. If they just look for your fastest segments for a distance you could have a 5K segment inside your 10K segment that is faster than your actually 5K for the race (especially if you overdo things on the bike) to where your 10K would count twice and your 5K wouldn't get counted at all.  I did notice that they do a 10K-40K-5K rather than a 5K-40k-5K like they do in outdoor races.  I assume that is so they don't have two segments at the same distance to make filtering through the data easier. 

So...I have as many questions about these virtual traces as I did about triathlons before I did my first one.