Online application

So today we start the visa app. I'm already confused. It asks Marital status. Even though I'm applying for a fiance' visa. I put Single correct? My fiance' seems to think unmarried partner is appropriate. Help?

Also where it asks Place of Issue and Issuing authority
Are they looking for USA and United States Dept of State?
Sorry I'm working on zero sleep

Marital status is single.

Correct on the other question.

I put Single correct? My fiance' seems to think unmarried partner is appropriate. Help?

No, unmarried partner is for a completely different visa, whereby you are both living together legally in the same country and have no intention of getting married.

You are not married yet (you are coming to the UK for the purpose of getting married), so you put single.

And just to make sure you know (and haven't selected the wrong option), at the beginning of the application, where it asks for your purpose of application etc. you select:

Settlement -> Settlement -> Marriage

Thank you few more questions:
Where they ask both my parents nationalities. is American appropriate?
and
Have you been granted any UK visas/ EEA Family Permit in the last 10 years?
I would tick no since it's only been entry clearance correct?

USA.

Have you been granted any UK visas/ EEA Family Permit in the last 10 years?
I would tick no since it's only been entry clearance correct?

This question can cause some confusion because you are actually granted a UK visa every time you enter the UK as a visitor, even if you didn't apply for entry clearance, so you should technically tick yes and list all your visits to the UK.

However, I don't think it actually matters all that much whether you tick yes or no because people here at UK-Y have done both in the past and it doesn't seem to have been an issue either way.