I usually use the 12V versions, presumably the USB ones have smaller value resistors.
The single colour ones have a supply and 0V and can be cut at 3 LED intervals, and, if waterproof, the clear coating can be stripped off and new leads soldered.
The variable colour ones have RGB and 0V, and are usually connected with pins and sockets. If you look on ebay for LED strip connectors, you should be able to understand the possibilities.