When exporting, after you've named the file there is a panel which asks about Anti-aliasing options. You might find one of these options gives a better result than others depending on the image you're creating so it's worth changing them around to see which options gives you the result you're after. This is the same line, saved with two different anti-aliasing options, you can see the one on the right is much smoother. For the text I'm guessing it's due to it not being a solid, but an outline, I expect someone else will have a better answer than this for you though.
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