Upgrade from Windows 10 professional

[Eric]

Will upgrade to 11 include all the functionality I have in Windows 10 Professional?

 

[Trouble]

I suppose that would depend on your definition of "functionality".
There are some things that have been deprecated or removed completely.
There are some problems with some third party software.
Some problems with some hardware components (internal as well as external attached peripherals)

Early days with some growing pains not necessarily unusual or atypical for a new Operating System.

My suggestion would be...
IF at all possible, sample it in a Virtual Machine environment (Hyper-V, Virtual Box, VMWare Player, etc.)
OR at the very least, create a known good, complete, system image so you have a strong fall back position.

Technically you have 10 days to revert back but that's not something I would blindly rely on.

Other's may disagree, and of course your mileage may vary.

 

[Attys]

If I upgrade and choose a non-clean installation, will my personal settings and documents remain? Or my third-party programs?

 

[Trouble]

If I upgrade and choose a non-clean installation, will my personal settings and documents remain? Or my third-party programs?

In a perfect world.... sure.
In fact that would be the primary reason for choosing to "upgrade" rather than selecting a custom clean install, but...
As I implied above, intentions and plans do not always survive very long after first contact.
"Everybody’s got a plan until you get punched on the nose”. <Mohammed Ali>
SO
When considering going forward with "a plan" as significant as upgrading the Operating System of your computer, especially one that contains huge amounts of personal / critical data, then you want to have protected that data and by extension yourself against any and all unintended consequences.

Use one of the many available imaging software products out there, both free and commercial to generate a known good full system image to a safe external source.
AND
By "known good" I mean that after the image is created, make sure that you can open / mount the image and browse it and confirm that you can open and view various items that you consider critical, whether it be documents, images or even music and video.
I would probably even supplement that with a simple backup of all those files and folders you consider critical (probably the contents of your Profile folder) again. Most imaging software supports that type of backup (data / files / folders) as well, but even if you have to perform a simple drag and drop, copy and paste process, you can never be too careful, when protecting your data.

 

[Attys]

Thank you for your answer
How much storage can I need for a backup? I mean, without pictures and other documents?
My system (SSD) and documents are on a different (HDDs) drives.

 

[Trouble]

How much storage can I need for a backup?

That depends on the amount of USED space on the disk that you intend to image.
IF you have that information, you can generally assume that you'll need about half that for hosting your image.
Most of the top tier imaging software use close to a 2:1 compression ratio when they create an image.
There are other factors that come into play as, some files are already in a compressed state and very little additional compression can be applied.
Just plan on a 1:1 ratio and test to see what your results are.
Avoid spanning your image across multiple resources. While some software supports spanning a backup, it just introduces an extra and unnecessary complication.