EU/EEA citizens have the right to work and live in Sweden provided they are able to support themselves, either by work or by other independent means.
Swedish ID number
Once you have moved to Sweden and intend to live there for a year or more, in most cases you are required to register with the Swedish Population Register (Folkbokföringen). The Register is managed by the Swedish Tax Agency (Skatteverket). When you register you will get an ID-number, which is a necessary part of daily life in Sweden as it is used in all transactions with authorities, shops, estate agents, banks etc. Registration at the Population Register can only be done after you have moved to Sweden. Read more on their website: Population registration in Sweden
Finding a job and working
The website of Arbetsförmedlingen contains useful information on how to find work in Sweden and the Business Sweden website has information on starting and running a business etc.:
Arbetsförmedlingen
Business Sweden
Swedish Taxes
Information on Swedish taxes can be found on the Swedish Tax Agency website: Skatteverket