I will try to help a bit but in general, you might want to take a look on more powerful editors. My choice is TeXstudio which supports line spacing in % as well as font size, scrolled zooming (like in Word), and many other settings.
But back to TeXworks:
The answer to your question on line spacing seems to be "no". At least, I could not find that. But there are other things you might tweak to your needs.
Just go to "Edit->Preferences..." and you will open a pop-up called "TeXworks Preferences". In the panel "General", you might want to increase the size of icons, just in case, those are too small for you. In the panel "Editor" you have some configuration possibilities regarding your text window and the used font. You may switch the font and its size which both might effect the line spacing as well. Just give it a try. In this panel, you may also change the default indent (Tab width) and toggle on syntax coloring and so on. Just set everything to your needs.
It might be that you will have to restart TeXworks in order to see some changes. And you mustn't be afraid on doing any harm as there is a "Restore Defaults" button in the lower left corner which will bring you back from Comic Sans to whatever the maintainers of that editor see fit.