Bond yield = return on investment in bonds. Bonds are safe investment instruments, as they give assured returns. So when economy is growing, people don't want to invest in bonds as investing elsewhere (eg stocks) will give more profits. So few people buying bonds, less demand for bonds, falling bond yields. But when economy is performing poorly, other investment options are not as lucrative. So people start investing in bonds.. Demand for bonds increase, their yield increases.
Thus bond yields are inversely proportional to economic growth.
Going by above logic, 1&3 follows.
