Can I set entries to be viewed or edited only by certain users?
Yes, By setting up different users to play different roles in each sheets. If a user's role is Survey User, he can only see the entries that he is the owner of, and if a user's role is Bulletin User, he can see all the entries, but can only edit the entries that he is owner of.
By default, a user is owner to only entries that he created, but by changing the input type for one of the fields in the form to Select User or Select Group and choose Set selected user as entry owner, owner of the entry can be added as the entry is created or edited. You can also change the owner of a field to a group, this way all the users in the group will be able to see or edit the entry as the privilege is assigned to them when this field is set.
Please check our documentation on access rights for more information.