What size sails and boards

430 would be a better size for your wife (this is a guess based on her weight). If you are using sails from 4.7-6.5 sqm, a 430 would be best for you also. If you are both using sails from 6-7.5 sqm a 460 would be better.
2 second hand masts

I think you'd be better getting more of everything (second hand) as long as it is compatible and in reasonable condition. Gear between 3 and 5 years of age is cheap and will perform well. This way you and wifey will be covered for more conditions and can spend more time on the water and less time on the beach waiting!