re: For an entry which didn’t has all of its data uploaded by CSV import.
If I go to ‘manage’ and click on ‘edit’ then click on ‘update’ without making any change to the entry data.
If there is a page caching plugin being used or server-side page caching being used, that could be the cause, flushing the page change after making edit would be necessary.
re: How to get labels displayed for ‘line 2’ ‘line 3’ ‘zip code’, ‘state’and other fields present in first row of CSV import?
Sorry, I am not sure I follow? Do you mean when they are displayed on the site’s frontend in the template? If that is the case, the only way to do that would be edit the template to show such labels which would be a somewhat involved solution requiring you to know PHP intermediately well.
re: I will also need to rename them
This can be done pretty easily, see this QuickTip. This basically would only affect the admin add/edit entry form though.
Hope that helps!