The supply is 220-240 volts, depending on where you are you may have a different provider, CLP or Hong Kong Electric. You will need to get them to come and read your metre or connect the service, sign and chop your contract and pay a deposit, which is repayable after your final meter reading.
Well depending on what type of business you have, but basically the same will apply as your electricity provider. Any equipment will be subject to safety and compliance checks. On some of the islands such as Lamma, LPG gas comes in a bottle, so keep a spare!
There are a number of choices of providers, the majority offering deals in what is a very competitive market. You could spend hours deciding on whose contract you're going to sign depending on the breakdown of your possible call profile. If I have any advise is get someone local to sort it out and go through the negotiation otherwise it will drive you nuts.
If you change provider you can keep your number. it is possible to buy a phone that is "unlocked". For business travelers and visitors alike, there are "pay as you go" options, some providers are now offering "data" services for picking up e-mail and web browsing while you're on the move during your visit to Hong Kong and Mainland China.
There are an increasing number of options for Internet and Wi-Fi for visitors to Hong Kong. Some are free, but you're required
to make a purchase before you use the service. look out for the signs in the windows of coffee shops, cafés for what's on offer.
As for Wi-Fi, the Government rolled out a program for Wi-Fi to be available at Government buildings including the libraries sometime ago. It's a free service, but I'm told signal strength can vary.
Same as electricity that you will be required to pay a deposit, repayable when you leave. Everyone is on a meter and yes you can drink it, but most people use bottled water out of preference.
Most of Hong Kong's mains water is actually imported from Guangdong's East River in China. Hong Kong's water meets World Health Standards and is considered to be one of the safest in the world. Water is treated with fluoride and has traces of chlorine to prevent contamination. Toilets are flushed with sea water, all very environmentally friendly.
Bills will carry a late settlement surcharge, the bill is due when it was issued and you will be disconnected if you forget. Reconnection does take time and there will be a charge.