Felku, welcome to the forum!
When it comes to Mozarella, the key is reaching the right level of acidity -- if the acidity is too low, the cheese will not stretch; if it is too high, it will fall apart. The goal is a pH of around 5.2.
One way to achieve that level of acid is by letting the thermophilic bacteria create it -- they eat the lactose (sugar) in the milk and convert it to lactic acid. Of course, it takes a bit of time to reach the right level, anywhere from a couple of hours to overnight, depending on conditions.
Adding acid to milk to make Mozarella is a shortcut, allowing you to skip the bacteria altogether (although some people do some of each). This is where the "30-minute Mozarella" comes in.
In theory, both should work. For what it is worth, however, I have had very poor luck with 30-minute Mozarella (adding acid). I have had much better results with letting the milk culture -- but of course, you have to keep an eye on it so that it doesn't go too far / too acidic. A pH meter definitely helps, though there are ways to test without a meter.
Perhaps an even more important point is that the taste of the bacteria-ripened Mozarella is far, far better. And if you add a pinch of lipase, even better yet!
If you search on the forum, you will find quite a lot of posts reflecting on experience with various approaches to Mozarella -- enjoy!
P. S. I visited PR a few years ago, and loved it -- we have been wanting to go back!
