1.5 - SINGLE
(unmarried partner is a completely different visa which you don't qualify for since you must have lived together for 2 years before applying)
6.2 - no, just list the dates of the trip
6.18 - you cannot pay for treatment you didn't have, so probably just leave it blank
7.18 - if you are engaged, then yes.
8.1 - yes, because you are a US citizen
You can emphasise your intended travel date in a cover letter - in bold and underlined

. You could also highlight it on your printed online application form
Appendix 2:
1.5 - put June 2013 for when the relationship began and then April 2014 for the date you first met
1.16 - yes, not applicable... that's only for the unmarried partner visa where you have to prove you have been legally living together for 2 years
1.18 - put NO... because you do not yet have the right to live in the U.K.
2.8 - I'd put: 'yes, once I am married and have the FLR(M) visa that allows me to work'
3.11 - this is the figure you are relying on to meet the income requirement and is backed up by his employer letter and payslips
3.12 - YES - because if the answer is no, you cannot qualify under Category A and will have to use Category b instead.
It's about being employed by the same company for 6 months... not when he got the pay rise. If he has not been earning the higher salary for 6 months at the time of application, they will only consider his previous, lower salary towards the requirement. As long as the old salary is more than £18,600 per year you will meet the requirement.
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