Generally, as long as you want. Some counties (UK for example) allow citizenship to be revoked by the government unilaterally (i.e. they think you're a terrorist, and you have citizenship in Another Country. Cannot lose U.S. citizenship unless you revoke it, in person, outside the U.S. at an embassy.
If you hold German citizenship, whether dual or not, then there are no occupancy requirements.
You can apply for dual citizenship to the USA and almost any other country. Many more people than you might think hold dual citizenship. But the road to dual citizenship, with only a few exceptions, is long, twisting and full of "gotchas".
Yes, as long as you are not a defector.
The US recognizes dual citizenship.
Since you have British citizenship, for an unlimited period of time.
Yes, Ghana recognizes dual citizenship, but with certain restrictions. Ghanaian citizens who acquire citizenship of another country after the age of 18 may hold dual citizenship, but they must apply for a dual citizenship certificate. However, individuals who acquire Ghanaian citizenship through naturalization or registration are not allowed to hold dual citizenship.
India does not allow dual citizenship.
Yes, Thailand allows dual citizenship.
Yes, Poland allows dual citizenship.
Yes, Venezuela allows dual citizenship.
Being already a Filipino citizen because of Dual Citizenship, You can stay as long as you like.
Dual citizenship is when one has citizenship rights in two countries.