Well this one is easy enough to remember! Seems like it could be directly related to the English word...
sure sounds like it.
The words come from a common Germanic background. They are related to ”ljud” and ”loud”
If I wanted to say "I am listening," would I write "Jag lyssnar" or would I need to include är? And if it's the latter, how would I write the sentence?
''jag lyssnar'' is correct.
Only one present tense in Swedish. You never ever ever construct sentences with subject + är + another verb the way you do in English.
She hears should also be accepted