Do you still require a work permit if you get residency as a result of buying a property in Mauritius?

Yes.

There are 2 schemes which allows foreigners (non mauritians) to buy properties in Mauritius. They are:

1. IRS (Integrated Resort Scheme)
2. RES (Real Estate Scheme)

With the IRS, you need to invest a minimum of $500,000 (US dollars) and you'll get a resident permit which is valid for as long as you own the property. The RES does not have a minimum price tag attached to it though but you do not get the benefit of the residency permit; you may apply for one though provided you meet certain conditions.

Both schemes do not give the right to work to the buyer. They should apply for an Occupation Permit if they wish to do so.

For the second part of your question, as long as you have not renounced your mauritian citizenship, you do not need any visa to enter the country nor do you need a permit before you can take up employment here.