This may be a dumb question, but here goes: my wife is an existing Verizon customer, and gets a significant discount with Verizon through her workplace. Best Buy has the new iPhone 5 on sale; if I buy it there, can I add it to her account and get the discount as well, or do I have to purchase the phone through Verizon?
do you mean a discount on her plan? or on devices?
but for your questions
1. yes you can add it to her plan at best buy
2. the discount she gets only applies to a primary line
a. for share everything plans it applies to the data portion, not the phone access fees
3. the discount will still apply as it does