To answer the NLB question, the only NLB you need to handle is for web traffic to your Web Applications (potentially including Central Admin). Use an NLB hardware appliance or HA Proxy -- I would not recommend using Windows NLB. Services, such as Search, MMS, etc. are handled by SharePoint's internal load balancer.
I would strongly suggest running all of ...
I would go with custom min role as you have two Sharepoint servers, with custom role you will get options to enable or disable the service you want to.
I am not sure which service application you want to use in you farm, but you can check this link if any other minrole is good for you.
Try running this one liner in PowerShell.
From here: https://blogs.technet.microsoft.com/victorbutuza/2009/08/26/crawl-schedules-do-not-work/
The powershell does the same as the code solution that the article provides.
Did you have a custom solution/feature related to "VDR_Mail_Event_Solution" on you SharePoint 2013 farm?
If you have deployed custom solutions/features on your SharePoint 2013 farm, to make sure them work on your SharePoint 2016, you need to re-deploy them on your SharePoint 2016 before you mount database on SharePoint 2016 farm.
Or, if you don't continue ...
this is not an answer but I am new here and cannot post a comment yet. I literally made this account to suggest trying the following. But it is not a solution so please be kind and don't downvote, just ask me to delete if that's what should be done.
Assuming you've tried this in other browsers (like FireFox/Edge/IE) to isolate that this is indeed a Chrome-...
I recommend setting up a search schema in order to carry out more precise searches. By default search schema only crawl text fields. For instance Title:Doc1 as mentioned in the previous answers. However, it is possible to accommodate for other data types by modifying existing schema groups.
Microsoft already has some decent documentation on managing search ...