How to fix errors after transferring a Bitrix site to another hosting?

Question

1C-Bitrix

The task is to transfer a site developed on Bitrix to another hosting (Beget).
There is very little experience with this CMS. I mainly worked with the Laravel framework.
What actions did you perform:
On the working site, I made a backup from the admin panel, except for the following:

I split the backup into parts of 100mb.
On the new one, I deployed a new project, deleted everything from it and placed the restore.php file in the root.
When restoring, I specified a link to a backup. Indicated to which database and how to connect.
In the admin panel, I replaced the domain name with a new one (so far I decided to deploy it on a temporary domain, because in the near future there is no access to that domain in order to change the DNS settings to Beguet's).
There were no problems here.
What I encountered immediately after the transfer:
White screen!
This problem was solved by disabling the module with ads.
The lesser of the evils.
I noticed that the templates are different from those on the old hosting.
I manually downloaded the templates from the old site and transferred them to the new one.
The site indicated templates and conditions for them similarly to the old one.
After that, only half of the site header loaded, because. in header.php script crashed on method call The error said that too few arguments were passed to the method. Without hesitation, I gave him two additional false'a. After this menu, he was still able to load the rest of the site. Why could this happen? On the old hosting, it worked with one argument. After I noticed that when I click on any link, this pops up: Again, he doesn’t have enough arguments.
Obj::GetMenu(false);

It was useful to dig into the sources, I found that in addition to the bitrix folder, there is a bitrix_personal folder with the following content:

The templates folder just contained those templates that I had transferred by hand before.
How it works? I do not understand.
One more question. In the top menu of the site there are links that are available in the admin panel in the "Site Content". But besides them, there are 3 more menu items that stretch from God knows where. I can't even imagine where to look for them. And they need to be edited. In edit mode, this menu is not editable.
PS
Among other things, the site works ten times slower. This is 100% not due to hosting. I have more than ten projects deployed on Beget and everything works quickly and stably.

Answer 1

There is a special script for transferring instructions here https://dev.1c-bitrix.ru/learning/course/index.php...
When creating a backup, it is better to leave the default settings, if the license is active, then it is better to backup to the cloud. And most importantly, the new hosting should be tailored for Bitrix, then there will be no problems.

Answer 2

Another moment!
In the bitrix/php_interface folder in the dbconn.php file, just asterisks (*****) were written instead of the database data.
Normal data is already written in the bitrix_personal/php_interface folder in dbconn.php.
How can I tell Bitrix to use bitrix_personal and not bitrix?
Because I just set everything up again, and he gives me this error:
Accordingly, on the old hosting, Bitrix takes data from the bitrix_personal folder, not bitrix