let me try and spell it out clearly so there's less confusion....
There are two basic options:
1) plug adapter
2) power converter
The question is when do you need one and when do you need the other?
Its not that difficult to answer- basically if your US device has a power supply rated at 110-220 V (or around there, some go lower), then all you need is a plug adapter (to get from the US shaped plug to the gigantor 3 prong British legacy thing they use here). If its 110-220V, it means that your device was made to work almost anywhere in the world no matter what the voltage is.
You can find this information on either the power supply (that black brick thing you plug in, also known by some as a 'wall wart') or on the back of the device. It should say something about Watts(W), Amps(A) and Volts (V), in this case you're most concerned w/ V's.
As mentioned, HK adapters can be bought at many places in HK for ~HK$1-2, so if you can wait a day or two, don't even try to find them in the US, cause they'll cost a lot more there.
Every laptop I have ever seen can handle ~110-220, you'll probably just need a plug adaptor for that. Many cell phone chargers are too.
IF your device doesn't handle 220, then you'll need to either change the power supply with one that does or buy the voltage converter(ok, I guess that means there's really 3 options). As mentioned these voltage converters can be large, heavy and expensive. You can buy small, cheaper travel ones that can be used for shavers, etc, but they are NOT good for long term use of electronics that draw a lot of power. (fire hazards, possible damage to the devices, etc).
In the case of your phone charger for example, it may be easy to just get a replacement here. There are tons of stores selling replacement chargers (either original manufacturer or generic brand ones) for reasonable prices (less than US$5 probably).
As far as the power strip goes: I'm not sure what the guy meant, but what you can do (and I have done in my house), is bring a US power strip with you, and use ONE adaptor to plug that directly into the wall in HK.
But the key to remember is that this turns the power strip into a 220V power strip, so you can only plug in 220V-safe devices (since we're not doing any conversion). This simply saves me from having to juggle 5-6 adapters to plug in all my 220V-safe computer equipment, which is all stuff I brought from the US.
(Several years back, I once was staying with a guy here who did something similar but he thought 'US shaped plugs means you can plug anything from the US', and he ruined my CD player by plugging it in. So be sure to check before you plug-in!)