What US taxes are applicable to overseas property/ assets of a US
Citizen? and what are the related penalty?

This is a comment and not an "answer" to your question, and, of
course, it is neither legal nor professional advice, as you can read
in the disclaimer below.

Basically, as US citizen is taxable on world-wide income.
IF you are asking about real estate property, in double taxation
agreements between other countries and USA, income and taxes resulting
from real estate are excluded, local taxes applying.

The principle of most double taxation agreements is to allow the
tax-payer to offset taxes in one country against higher taxes due in
the other country.
I.e., he just ends up paying the amount of tax due in the latter country.

Here is the IRS site with such agreements (actually, treaties for the
avoidance of double taxation).

Some countries have a tax on wealth, i.e., on capital assets.  I don't
know how these may apply to non-residents and non-citizens.
You should also know that there is an exchange of information between
the IRS and tax authorities in some other countries.  For example if
tax is being withheld on dividends in a country, this may be reported
to the IRS.

If you have questions about specific countries, maybe I can help.

Is there any centralized source of information on which countries
exchange information with the IRS?  Is it safe to assume that most
countries with tax treaties with the US do share information with the
IRS?  I am particularly interested in New Zealand, Japan, Australia,
and Canada.

My apologies for not adding the website mentioned above.

http://www.unclefed.com/ForTaxProfs/Treaties/

For each country you can click on the Convention and also on a
technical expanation.

I think you will probably find an article such as Art. 25 in the
Convention with New Zealand and Art. 26 with Germany that mention the
exchange of information.
I know that the German tax authorities receive from the IRS standard
information on income that is reported to the IRS, such as dividends,
etc., etc.  Some "one-off" income reported on paper forms to the IRS
by S corporations may be missed, but don't bet on it.

I hope this helps.  Again, I am sorry that I oversaw posting the site.

Regards, Myoarin