Yogurt Results!

One thing I look forward to in my life is goats: the breeding, honing, loving, and milking of Kinder goats. One of the things about raising and milking goats that i look forward to is making my own cheese and yogurt on a regular basis.

Before i get into the success or failure of my yogurt attempt, i just want to mention the starter: You can make yogurt with a few tablespoons of already made yogurt, or with freeze dried bacteria starter stuff available from various cheesemaking supply stores like this.  So i made yogurt - i should use some of it to make a new batch within a week. Alas, i only buy milk every 2 weeks so i'll have to start again. Could i use the yogurt as starter if it has been frozen? I don't know - can i? Since we don't eat a ton of yogurt, i will be turning about half of it into frozen yogurt 'pops' for delicious hot afternoon protein snacks. The rest will be used up in recipes over the course of the next week, or just frozen for later use. I'll report on the tastiness of the post frozen regular yogurt later on.

And now: the results:

I would say this was somewhat of a blend between fail and success. The result is a tasty, sliiightly tangy, sliiiightly thick milky substance. The vanilla tastes like vanilla. The plain tastes like plain - they all taste more like thick and creamy milk than yogurt. I took Erin's advice and did not incubate in my car. I put the box filled with quarts and fleece in the driveway. I am wishing i had left them in the car - it was only 93-95 outside yesterday, i think the car would have been closer to 115, the recommended temp for incubation.
I am now faced with a question, or rather a few questions:

1. How am i sure this is safe to eat?
2. Is the lack of thickness a fine product for consumption? i know that homemade and bulgarian yogurts are both thinner than the store stuff - and the longer you ferment the tangier you get - but is there an amount of tangy that is required to be sure it's safe to eat?
3. Will the cultures be killed if frozen? I plan on freezing about half the yogurt to eat frozen and to save for next week.
4. Would it be better to risk overheating/killing the culture, or to risk underheating and creating some kind of 'danger zone' bacteria filled milk substance?

Fermentation is a strange art. It's essentially 'making things go bad' in order to make them store longer or have more health benefits. But how do you REALLY know if it's fermented to the point of healthful, or fermented to the point of sick-making?

Next time i'll try heating pads, the oven, or maybe a yogurt maker, or maybe i'll try the inside of the car again. But next time i'll be trying out pints or just 2 quarts so that i'm sure not to waste at least half a gallon.

Do you have any awesome yogurt making tips to help those of us newbies on our way to greater success?