A rig is a device or equipment designed for a particular purpose. A Radio Rig is station equipment used for radio communication. In case of Amateur Radio Operator, it can be HF, VHF, or UHF. Generally, radio rig is a station or a base station equipment that can be professional or homebrewed.
The radio shack is a setup of Ham equipment at any Ham QTH. A room or a structure used for housing radio equipment is called Radio Shack. Generally, a shack consists of HF, VHF, UHF radios (all or whichever is available) arranged in ready-to-operate condition along with few handheld radios or walkie talkies and the other necessary equipment like power supply, batteries, tuners, SWR meters etc.
It is not necessary to buy an SWR meter for VHF or UHF users. Once we tune the antenna using an SWR meter, there is no need to check the SWR repeatedly unless there is some damage to the antenna. However, in the case of HF, the SWR meter is always handy as with an SWR meter attached to HF, we are always sure that every time we are throwing enough power.