1) VAF1F i think your looking at the wrong form ,if i'm right that's for people just to come to the uk and marry,its not for settlement

2) yes you need vaf4, fiancée visa is valid for 6 months, you must marry in the uk within 6 months and then apply for FLR which is valid for 2 years, and in those 2years take 'the life in uk' test and apply for ILR. but there's changes happening this year which will effect you. no if she marries within 6 months she doesn't need to go back to the phils

3) i think so its ok as extra income.