I think going to 63 C will help the cheesemaking, but I think the letting it sit overnight at high temperatures will not contribute to its safety. You can make a chiller very easily by buying some copper tubing and bending it into a coil. Run cool water through it and it will chill your milk in 10 minutes or so. Home beer brewers use them all the time. Search for plans for a "wort chiller". Some of them are very simple.
Raw milk is difficult to talk about. Pasteurised milk is about 1000x less likely to cause disease than raw milk. However, it's *still* quite unlikely. The US has about 2 million drinkers of raw milk. It typically gets about 1-2 deaths a year on average. Normally there are no deaths for years and then you'll get 10 all at the same time. You don't only have to worry about death, though. You can suffer serious organ failure as well and long term health problems. But again, it's very, very unlikely. It's like the lottery. *Somebody* will "win", but it's very unlikely to be you. From a public health perspective, banning raw milk makes sense to some people because you will guarantee to have less deaths. To people who want to drink raw milk, it doesn't make sense because they were already unlikely to get ill. It's important to realise it's not just elderly or unwell people who are at risk, but the risk is still low.
Having said that, raw milk has bacteria in it. Some is the bacteria that we *want* -- bacteria that will make yogurt or butter milk. Some of it is bacteria that we don't care about. Some of it will make you ill. When you are working with raw milk, you want to keep it in a state where the bacteria you want is favored. If it grows quickly, then the other bacteria can't survive as easily -- they all compete for the same resources. I don't work with raw milk, so I'm not the best person to talk to about this. However, generally you want to use the milk as quickly as you can after it has been milked. If you can't use it within 4 hours, then my understanding is that you should cool it. But either way, you want to use the milk within a day or so.
Pasteurised milk is a double edged sword. It has no bacteria in it at first. However, that means that it is vulnerable to bad bacteria. If you have milk that you've pasteurised and you just let it sit at warm temperatures, it *will* pick up bacteria and that bacteria will grow. It doesn't have the *good* bacteria that's in raw milk to compete with it. Both situations are risky and I couldn't tell you which one has more risk. For making aged cheese, my own personal preference would be to use raw milk. However, you will have to do your own research to decide what makes the most sense to you. By far the least risky is to pasteurise and cool quickly. After that, it's hard to say.
Sorry I can't give you absolute answers. It's not that kind of thing. I hope you find a way of working that works well for you!
