Questions on Aura, Salesforce configurations

2>A profile has contact delete permission.This profile is assigned to 2 users but one user should be able to delete contact other should not .How do you achieve this
For the same scenario above let's say I have a lightning button to delete contact and I have made the class as with sharing. In this scenario what happens when I delete the contact as the two users?
As per my uderstanding with sharing can only add restriction based on OWD and sharing rule. not profile. if user has delete access on profile then he will be able to delete.
We can do this using 2 methods either through UI/Apex
Using UI -->
Making a Hierarchy custom setting(Most Restrictive Access Priority User>Profile>Organization) and then select the User for 2nd user that you want to restrict the delete permission
Using Apex -->
You're right about the With Sharing (Like OWD/Sharing Rule only for records not for Field & Object Level)
For Object & Field Level Security below are the options
You can either use
1. Schema class method isAccessible,isUpdatable (Old Technique) https://www.apexhours.com/security-in-salesforce/
2. new Techniques (Using StripInaccessible https://medium.com/salesforce-zolo/stripinaccessible-the-great-new-way-to-enforce-security-in-apex-e2cf79cb9500
By adding with Security_Enforced keyword at the end of SOQL Query https://amitsalesforce.blogspot.com/2019/07/field-level-security-in-soql-with-SECURITY-ENFORCED.html)
3>What do you do when you have a req to display list of contacts on the UI but the columns and order of columns varies from client to client?
You can make use of API variable for LWC that will needed to add in .meta-xml file with same name of variable as in .JS file
or in Aura Component --> Make an Aura attribute that have same name as described in .design file. After that when user need to make more columns then user can edit the page (Detail page) and in right side there is column on which they can enter number of column values
You can either set default value in design file.
4>How do you display 50k records on UI using Aura---- data table lazy loading??
You can make use of LIMIT & OFFSET Keyword when retrieving the records.
6>Suppose we a zip code field in account detail page. in that detail page we want to display another component that would show top restaurants in that zipcode. How can we achieve this?
In this case you can make use of LDS to get record field value. Based on value you can show top restaurants (Like you can invoke rest api zomato to show top restaurants based on zip code).

For 1st we need to use triggers as i understand the condition.

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