ברכות דף י"ד

The gemara asks whether someone who is fasting can taste אכילה ושתיה קביל עליה והא ליכא או דילמא הנאה קביל עליה והא איכא. From the gemara's question it seems that tasting is not considered eating but it would be considered הנאה. The gemara answers טועם ואין בכך כלום which suggests that the gemara concludes that tasting is not considered eating but that is all that is prohibited. Tosafos seems to have a different understanding however since Tosafos says that the reason that you can taste is שחוזר ופולט דלא חשיב הנאה מן הטעימה אבל בולע לא. In other words, according to Tosafos הנאה is what is forbidden but this is not הנאה.

1. Where does Tosafos see this in the gemara?

2. How does Tosafos understand the follow-up question of the gemara עד כמה טעמי, since in any event, one is not swallowing it, what difference does it make how much you put in your mouth?