You don't need to make payment links with your friends;
Absolutely right, and this is confirmed by the principal architects of Nouveau Ripple:
...we're not relying on community/social credit. We're promoting Ripple as a payment system based on gateways. The social credit system will always be there should people be ready to use it.
And
I think it's reasonable to only make "business-related" links...
Also confirmed by the Nouveau Ripple architects:
...the path will almost always be either:
Payer -> Gateway -> Recipient
or
Payer -> Payer's Gateway -> Middle -> Recipient's Gateway -> Recipient