you can get married but you cannot apply to remain here. you need to leave the uk and apply for entry clearance from turkey to come as the spouse of uk national.
No you can't. You would more or likely get refused if you get married before getting a spousal visa after you get married. So you would need to get that visa before the wedding, while on the tourist visa.
Yes
No- that is considered bigamy.
No
It is possible for a Filipino in the U.S. on a tourist visa to marry an American citizen. Getting married is usually easy, but being allowed to stay in the U.S. can be more complicated in this situation and may require the help of an attorney.
This visa is not necessary.
US citizens don't need visas to enter the US, so it doesn't matter what kind of Indian visa you have. The Indian visa is permission to enter India.
Yes, Indian tourist visa can be extended on medical grounds.
How long does what take? You need to be a bit more specific.
If you are married to a US citizen but your tourist visa is expired and you lost your I-94, you should immediately apply for a new visa or return to your country. Your I-94 is filed electronically, and you can get a new copy from the Department of Homeland Security. If you don't take action yourself, you may end up being deported and not allowed to return.
If he is still married to you, he is as much a citizen as you are, as separation is not the same as divorce. A marriage with a US citizen counts more than a visa does, as marriages last longer and are harder to end than visas.
If you plan on getting married in the US, file for a K-1 Fiance visa. It will take about 6-8 months.