11. What will happen if profile related to user U1 above in role hierarchy doesn’t have CRUD permission for object say A. User U2 below in his role hierarchy have CRUD permission to object A. Will user U1 will be able to see or edit record if Grant Access Using Hierarchies is checked for object A in sharing settings?
No.If a user does not have read or edit access to an object via OWD, a profile or permission set, they will have no visibility over an object regardless of their role and role hierarchy.
Always remember that User above in role hierarchy can see records of users below in hierarchy but operation which he can perform depends on permission on his profile (CRUD & View All & Modify All).
12. What is permission Set?
A permission set is a collection of settings and permissions that give users access to various tools and functions. The settings and permissions in permission sets are also found in profiles, but permission sets extend users’ functional access without changing their profiles.
For example, to give users access to a custom object, create a permission set, enable the required permissions for the object, and assign the permission set to the users. You never have to change profiles, or create a profile for a single use case. While users can have only one profile, they can have multiple permission sets.
13. Is it possible to restrict permission for users using permission set?
No. Permission Set always extends the permission.
14. If you have two record types for an object, do you need to have two page layouts for that objects?
No. It is not required but if user want different UI for different record type then we can create 2 different page layout and assign page layout to profiles based on record type.
15. If a user does not have access to a specific record type, will they be able to see the records that have that record type?
Yes. Record type controls only visibility of record on UI not its access to users.