What to look for when buying a laptop?

I've been on the laptop several times despite consulting in the business on the nose and try so this time to make myself smart, but despite the many articles on the Internet, I'm a bit overwhelmed…

I would like to work with the laptop with Cubase, but you need an i5, but in addition I have no idea what to look for.

In my present I have an SSD… Can you rebuild?

Are there any memorials known for their reliable services?

I had my laptops more often in the workshop than at home, very annoying!

I look forward to your answers!

Well that's a lot of questions at once I personally find the Windows surface on handy because you can carry it around portable from workshop is also very easy what aba there's unfortunately no cubase

Well, "i5" can mean anything. Especially with laptops, there are sometimes huge differences between different i5 processors. An i5-8400H is e.g. More than twice as fast as an i5-7200U. An i5-8600 (also available in some notebooks) would be three times as fast as the i5-7200U.
i5 has no meaningful performance, especially not with notebooks.

What do you mean by "can you rebuild"? If you think if you can swap the hard drive / ssd, maybe.
Arrives on the notebook. My one laptop has a removable 2.5 inch HDD, which I could replace with a ssd, my other one has a ssd soldered and additionally offers the possibility to install a m.2 ssd.

There are brands that generally have higher-quality notebooks, and brands that have rather cheap notebooks, but you should not rely on that. Since you should look at reviews.