Randy Calvert

This is done through a custom theme. There is no default feature that adds a second nav menu. 

It would require custom theme and be something you would have to style the CSS and such yourself. 

OK.  Click the Disable Customizations button.  It will turn off the plugins for now and switch you to a default theme.  If everything starts working again, you know it's one of the things highlighted in yellow.  
You can then turn on the various items one by one till you find the one causing problems.  

Have you tried disabling all 3rd party plugins and switching back to a default theme to see if the problem still occurs on PHP8.x?  
Once you've disabled everything, enable various items one at a time until you find the problem child.  

They are not tables used by active IPB default install. Try renaming them to something else like OLD2 for a week. If nothing is broke by then, delete it.   If something breaks, restore the original name and you can figure out what is using it (such as a plugin or application).

Unless it’s continually happening for long periods of time, it’s fine. It’s saying you made a request to Facebook, but it timed out with no response after 10 seconds. 
If it happens infrequently, it’s most likely just a temporary routing issue between your server and Facebook. If it’s ALWAYS happening, a firewall or something similar is blocking your server from reaching the Facebook endpoint. 

Not sure what you mean by database address.  If you are trying to change your database server info (host/IP) and/or database username and password...  that info would be in your conf_global.php file.  
$INFO = array (
  'sql_host' => 'XXXXXX',
  'sql_database' => 'YYYY',
  'sql_user' => 'ZZZZ',
  'sql_pass' => 'AAAA',
  'sql_port' => 3306,

If you are ABSOLUTELY sure you have the correct files, you can skip the integrity check by adding
\define( 'UPGRADE_MD5_CHECK', FALSE ); to your constants.php file.  One the upgrade is complete, remove that line so that it does not always skip it going forward.  

ACP - System - Settings - Contact Us
You can use the following:
Send email to incoming email addressThe email will be sent to the incoming email address set up in the Email Settings
Send mail to these addresses
Link to a URL
Create Support Request

Either rename it in the Language settings or remove the item and add a manual external  link with whatever name you like. 🙂

The Products from commerce should be able to be renamed from the language settings in the ACP. It may be possible to rename the 3rd party one if they used language strings when creating the app. 

When I try to access the link, I get an invalid SSL certificate. It’s trying to say it’s really:
cdn-edge-us-central1-l0f4.cdn.siteground.net
After ignoring that warning, I see it trying to load the old domain. After you had your host switch the domain, did you edit your conf_global.php to provide the new one?  Afterwards did you rebuild your system cache in the ACP?

Search for the account in the ACP. When viewing the Member record, if the account is still locked, you can unlock it there. 

Locks are generally temporary so it may have already unlocked. 

IPB does not have any sort of direct integration path, however there looks to be options through Zapier. 
https://zapier.com/apps/monday/integrations/invision-community

ACP - Commerce - Payments - Settings
Choose Email Copies and then select what types of transaction emails you want and what address should be BCC’ed. 

Number one is not “exposing” anything sensitive that is related to the server or app itself. It’s user level info or public knowledge data. None of those fields contain anything that is not already available elsewhere to that user as part of a normal HTTP request (either via header or body values).
Number two would be mitigated at the server or via a WAF. That is not a code level thing to check. 

Number three… encryption in transit is controlled by TLS on your server. The value would not be able to be read by a third party if HTTPS is utilized. Again the only group that can read it is the user for their own data if HTTPS is enabled.  The value is not from the database. It’s what is being passed from the form BY the user to your server. You can’t hash/salt it until the server gets it. Once the server gets the data… passwords are stored in the database in an encrypted format with proper hashing/salting. 

That is not a logo.  It's a favicon.  
ACP - Customization - Appearance - Icons and Logos

ACP > Community > Forums > Forums
Edit the forum you want...  in the "Forum Settings" tab, find the "Grid Card Image" option and choose an image.  

There is not any sort of officially supported 3rd party support ticket systems.  You would need to work with a third party developer to integrate whatever support system you decide is best for your community. 

It sounds like you created a custom link called “What’s New”. That’s not a default item in the navigation. Make sure you have permissions for the item set properly. 

Also remember you can create two “What’s New”. Only one visible to members and one visible only to guests. 

In order to document findings from the development team so that others can learn as well…. 
This is occurring because we don’t collect address information from our users.  (We don’t require it for tax purposes, we only accept payments from full site members, AND we prefer not to store sensitive PII data such as name, address, phone number, etc).  
The dev is going to propose a change where that requirement could be skipped if there is no tax setup defined/needed.  

You need to list your actual key followed by test install. 

In the Staff Directory in the ACP, you need to list each person by name instead of by group in order to see a title/biography.  If you just list the group, it won't the the extra details.  

Because they’re designed as one column setups instead of two columns. 

If this really bothers you, create a page in pages with whatever layout you want and make that section a link. 

In the mean time…. Review your title, the keywords, etc.  This might be a good time to review descriptions and other things that can help improve SEO.  
At the end of the day…. Remember that content is king.  
We ended up with a topic that got HUUUUUGE attention last summer.  It literally lead to a 20X increase in traffic for about a week and about $100 in AdSense revenue from that one page over a couple of weeks.  It’s impossible to predict if/when it will happen, but when it does…. Boy it makes the day nice. 😄 

That's not really a question for IPS support.  You're not going to find many "free" services out there.  Spammers abuse services way too much.  
You could try to use a Gmail account or something similar.  Or reach out to a few cheap hosting services and see what they allow for email limits.  Maybe just point your email at one of those accounts.