We must also thank you, open-source projects move forward because they have willing contributors! 
With regards to registering contributions: yes, it is ok to share a link to an unmerged PR - just mention that it hasn’t been merged yet, if I recall correctly, there’s a field where you can say that.
Addressing the other questions:
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there are two projects available. Please, choose the one you would like to work with, if you get selected for the internship, and plan a timeline on how will you address the task, over the 3-month internship. It doesn’t have to be a detailed timeline, just enough for you - and us - get some overview on how you will approach things. This isn’t written on stone, of course, and adjustments can be made along the way. You may use the internship tasks described on the project page on Outreachy to base your answer on.
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Do you have specific doubts about the community-specific questions, or are they not available for you to answer? If it’s the second case, please, let us know, and I believe that our great coordinator @sbhardwaj may share those with you all. If the questions are available, but you need guidance on specific questions, do explain where do you need more clarification, please!
Keep up the good work!