ButterpieBride - unfortunately there is a severe lack of good information about FFing.
There is a very very good leaflet produced by UNICEF which is about formula, different types, how to feed and how often. See here. (I'd recommend that you look at the one for HCPs which has much more info in it.).
I think it is important to provide evidence based advice.
Sure - anecdotal advice can be interesting - but the fact that people have used methods which are not recommended and their DCs have been fine is neither here nnor there.
There are mum's here on MN whose DC have had serious problems from formula and mum's who know of friends with similar circumstances.
Regarding sterilising bottles: the reason for sterilising bottles is that it should make it more likely that any bacteria on the bottles and in the teats is destroyed.
Properly thorough cleaning with hot soapy water, air-drying in a clean area should also remove bacteria.
I think the guidelines state to continue to sterilise whilst bottles are being used as it is difficult to ensure that teats are completely free of bacteria.
Obviously the risk to a baby of a D&V bug decreases as their own immune system improves.
Making up formula:
Formula powder is not sterile. The manufacturing process cannot guarantee to remove all bacteria. Some of these bacteria can cause fatal and dangerous infections. These are much more common in young babies.
Making up formula with water which is 70 degrees has been shown to decrease the risk massively. The lowest risk is to make each bottle up fresh. However there are guidelines for making bottles in advance, colling rapidly and storing in the fridge.
A kettle of 1 litre of water boiled and left for 30 mins will be 70 degrees. If the water is hotter than this then there is a risk that nutrients and vitamins can be destroyed.
Have a look at the NHS guide for HCPs.
If you want more details into the ins and outs then the Irish Guidance Note 22 is brilliant.
Use of a microwaves is not advised due to hot spots. I found it very easy to heat milk in a jug of hot water.
Lots of people talk about a method of making powder up with a smaller volume of hot water and then adding cold. What I would say about this is that it hasn't been tested (from a bacteria point of view) - it's not clear if the smaller volume of water can kill the bacteria.
Regarding cow's milk - it is not advised I don't think until a baby is 12m old. Having had to give up BFing I wanted my baby to have a BF substitute rather than cow's milk.