Adding salt to the driftwood bath has a two fold benefit. A) Not many organisms can thrive in both salt water and fresh water. So soakign the wood in a strong salt solution, then moving it to a freshwater solution, will kill most if not all possible microrganisms it may carry, and B) Salt water will 'cure' the wood preventing it from rotting. I admit I cannot explain the chemistry or biology behind this process, but it is a fairly commonly understood fact that wood that floats in sea water can last much much longer. For example, in the low to no current areas of the dead sea (very high salt content) sunken ships preserve almost perfectly for well over a thousand years... when wooden ships in freshwater lakes rot far far faster...
Boiling the wood is equally effective at killing microrganisms, probably even more effective. But the action of boiling is more likely to break down the wood as opposed to preserve it...
The more acidic water is the faster it will dissolve calcium based elements such as coral.
Typically, we would put a bit of crushed coral either in a media bag in the filter or mixed with sand/gravel as substrate. Water added after a water change should be treated with bakign soda to raise the PH/KH.
If you rely only on coral in the aquarium... when you add tap water, the PH will drop... then slowly creep back up over the course of a week... then when you do a water change it will drop... then it will slowly creep back up... repeat, repeat, repeat... result = constant PH swings that are bad for fish...
Chances are people will be eager to share with you their method of doing this alogn with the measurements they follow. Keep in mind that if your tap water is of a different KH or PH your needs will differ.
The best bet is to start slow and work it out yourself. Remember, with baking soda, a little bit goes a long way. Now put on your lab coat and start your science experiment!
