Hi Trefor.
Your fiancee's visa category will fall on Settlement then marriage.
Yes you do need to put a rough date coz on the form they ask for DD/MM/YYYY she intend to travel. You can put out any date, e.i. a month from the date of application.
Yes her main purpose is To get married and live with you permanently in the UK. Please try to be precise and concise with your answer coz the characters are limited.
I assume your talking about the Sponsorship undertaking form (SU07)? If so, this form is not necessary for fiancee visa application. It is only applicable for applicant applying as a dependant relative of someone settled in the UK.
Hope this helps.
Juvy
