Here is the reason of the revision.
1)
にっぽんばし is the destination to go to, not the location of the action "to buy" there. You can also use にっぽんばしに.
"The -masu stem + に + 行く" is a set phrase to mean "to go doing".
レストラン is the location of the action "to eat".
2)
を indicates the contents of the talk when used with 話す. ともだち is the target you talked with.