You got scammed, unless your iPhone is jailbroken you cannot get a virus.

What you should do:

1. Double tap Home button and delete Safari from multitask list

2. Go to Settings > Safari > Clear History and Website Data.

3. Never click on a link without knowing where it leads you to.

I could get one account online by removing it, and adding it again.

If I do that, I will lose all the emails that I put into special folders, correct?

I have not removed and re-added my main business account, as I need all those emails in their special folders, that I use as a to-do list.

PS: while I'm getting login error, I can send and receive email.

What the heck is going on?

PS 2: after an hour of so of login problem, the error messages disappeared.

Do Apple and Google fight sometimes?

Read the release notes for the update. This mitigates the problem in Safari. Since other browsers do not use Apple's rendering engine, they are not effected.

You can control what apps are permitted to use cellular data in settings>cellular. You can turn off cellular data usage for Safari and Mail, but you can not disable it completely for system services without turning it off completely.

If they're located in a home folder, they're specific to that account.

If they're located in the Library folder at the top level of the drive, they're global.

(156947)

go here and download Firefox then install it to your Mac. Set up its preference then use it.

Download Firefox — Free Web Browser

I find this very frustrating and that it’s impossible to change even with the settings in accessibility. Also the pinch to zoom doesn’t auto flow the text. I came from a 7plus and honestly I think this phone is straining my eyes. Apple needs to fix this.

You've installed what many  around here consider malware:

[loaded]   com.macpaw.CleanMyMac2.Agent.plist (MacPaw Inc. - installed 2014-11-28) [Lookup]

   [loaded]   com.macpaw.CleanMyMac3.Agent.plist (MacPaw Inc. - installed 2017-12-16) [Lookup]

Uninstall all Macpaw software according to the developer's insutricutiojns;

How To Uninstall CleanMyMac 2? Complete Removal of Mac Apps

How to uninstall CleanMyMac 3. Knowledge Base - MacPaw

Also uninstall DrCleaner.  Cleaning apps of any kind are not necessary and do more harm than good. See Eric Root's post in this topic: How to remove Dr Cleaner.

You can't see times (assuming that you are referring to Safari), you can only view dates (and, if today, 'this morning' etc.) via the history tab in the bookmark folder

disable any 3rd party plug-ins you have installed, quit out of Safari and relaunch Safari holding down the SHIFT key.