"Public Debt" is not an issue. It is probably one of the biggest economic advantages the US has. US dollars(which all US debt is denominated in) are issued by the US government. This means that it is impossible to "default", unless the government willingly chooses to default. The US doesn't owe anyone "real" resources. On the other hand, the US has acquired huge amounts of real resources(cars, services, electronics, clothing...) from (foreign) holders of US debt like China, Japan etc.

Yes, these dollars are capable of purchasing any resources available for sale in the US, but again, as a sovereign nation, the US is capable of imposing customs and taxes to regulate this flow as they see fit.

Debt issued by a sovereign nation which controls its own currency is completely unlike household debt. The US government is not revenue constrained. This means that it does not need to collect taxes in order to spend. Indeed, since all US dollars come from the government, the US government must spend first in order that there be any money to tax away.