Yes, you can.
If you need a discount code ($25 discount on your 3rd month' bill) pleass use: IDOUU
Yes you can have up to 5 lines on the same account. Or a separate account per person. It is up to you to decide.
Each new account can receive a new customer referral credit. So if you sign up first, then you can refer your wife. The choice is yours to make.
If you are looking for a referral code, please feel free to use mine 66KGA at sign-up. We will both be rewarded with a $25 credit once you have paid your second monthly bill.
So first thing you need to do is order your SIM card(s). Once you receive it, logon to complete the activation, and select your plan. Also you have to request the transfer of your old number and put in your referral code before confirming your activation because these 2 steps cannot be done afterwards.