No expert here, but :

1) No typical age for a black working line dog. You can try asking the breeder what age her mum was when she had her first heat. Your male should let you know also. And her vulva should swell also. Pay attention to your dogs and it's harder to miss it.

2) That I do not know because that first heat maybe funny. Usually you see a bloody discharge for about a week or more and then a clear discharge for about 7 days. Blood is the indicator, clear fluid is showing when she is receptive.

3) Again, she probably can't get pregnant until the discharge does clear, but do not take chances. I would say male outside and female inside because if the girl is outside on ehr own there is a good chance other male dogs will come to jump her. Take her out on leash and with constant supervision, especially when you no longer see blood.

4) With my girl I supervise her outside time after about 3 days of bleeding until she is back to normal. i.e. no more swelling of the vulva, and no more discharge.

5) I would say no contact, and no lox fencing, or no fencing at all. Just make sure they have no access to each other. putting them in seperate rooms is also a good idea.

Just some advice. 1) mark the important dates i.e. when you noticed swelling, first blood spot, blood stops flowing, clear discharge seen, and heat cycle is finnished. This will help you witht he other heats. Also not attitude changes, like clingyness or agression to strangers or even friends. Last you should look for physical changes like a shedding or a rash or anything different from the norm. even dulling of the coat. All these things will help you in the future when dealing with heat cycles and breedings. I can tell if my girl is commming into heat maybe a month before it happens because she sheds and then has red bumps on her stomach. That triggers me to take her to the beach a lot and whatever else needs to be done.