Will i get a proper interface (start bar etc) and no black screen where i must manually insert command lines?
Every Linux distribution I've ever dealt with comes with at least some form of wizardry required at the terminal interface (black command line screen). I've personally not dealt with DSL Linux, but I can imagine that some command-line typing will be required as with 95% of all other Linux distributions, especially since DSL Linux is a quite extraordinary Linux dist.
As for proper start interface (I assume you mean a desktop environment, GUI?), DSL Linux seems to have a variant of X - so in other words; yes, you'll have a graphical user interface, although limited and especially not as "flashy" as what you'd expect of a KDE or Gnome distribution such as (K)Ubuntu for instance.
I want it to be usable for the internet i have a usb wi-fi stick and from what i know it should come with pre-installed drivers for the stick.
Suggestions?
DSL Linux itself can browse the world wide web, but Wireless Fidelity and Universal Serial Bus support will definitely be an issue. If you're sure that it comes packed with pre-installed drivers for your Wi-Fi dongle, then the issue is non-existent. But such devices
usually require
much tampering with the terminal/command line and the text-editor and/or config files in order to work.
I suggest that you use the RJ45-jack (common Ethernet interface) if you have one available.
Is DSL the best linux for the laptop?
Both yes and no. With regards to your requirements, DSL is not
the best Linux distribution. But concerning the hardware of the computer (according to Google), DSL should suite just fine (at least in theory).
Your decision.