I believe the federal deficit will continue to grow significantly
during the next 10 years due to tax cuts, social
security/medicareexpenditures,increasing interest rates,etc.

What will be the impact of, say, doubling the federal debt over the
next 10 years on INFLATION, INTEREST RATES AND REAL ESTATE PRICES?

Most of the US debt is held by US citizens.  

These citizens for the most part would be investing these trillions of
dollars one way or another, and if they didn't have government bonds
many would likely have mutual funds/stocks or corporate bonds.  Stocks
and corporate bonds are investments in companies which in turn allows
them to buy capital, hire more workers and be more productive.  This
would obviously be a stimulus to the economy, so it is easy to see how
government debt slows down the economy.

INTERST RATES:  If the government has a large debt then a portion of
people's savings is in government bonds.  Money that would typically
be in a bank or invested in a company (stocks/mutual funds/corporate
bonds) is invested with the government leaving these companies in more
need of funds.  In essence the supply of money has been decreased
which raises the interest rate.

INFLATION:  As these companies have less funding (stocks/mutual
funds/bonds), they will produce less.  So in this case there will be a
smaller supply of goods but the demand will not decrease much.  This
shortage of goods helps cause inflation.

REAL ESTATE:  Typically, interest rates and real estate prices have an
inverse relationship.  (as interest rates rise monthly payments rise
and so people can't afford as much house so demand is decreased and
therefore prices fall)

Right now the US national debt is around $8 Trillion and GDP is
quickly approaching $12 Trillion.  In other large economy countries,
the larger negative affects of national debt haven't been realized
until the debt is as large as GDP (which unfortionately could happen
in 10 years).  But we can hold out hope that our leadership will get a
grip on spending before anything too serious occurs.