Double checking my work (phlogenetic inference)

This is from my genetics homework for phologenetic interference, I am given 5 questions to answer based on the phylogenetic tree provided. I would appreciate if someone can double check my work before I turn it in.

Here is the phylogenetic tree: https://imgur.com/nwiJPuG

Heres the 5 questions + my answer:

1.)  (a) Identify a monophyletic group (consisting of two or more taxa) on the tree.  Name the  taxa in that group.
    (b)  Why is this group considered a “natural grouping”?

For a) here is the monophletic group: https://imgur.com/OuOJbcW - Would the taxa be "Bat-SL-CoV" ?

For b) It is called natural grouping since it has a single common ancestor and doesn't exclude other taxa which have evolved from that single common ancestor

2.)  (a) Identify a paraphyletic group on the tree.  Name the taxa in that group.
      (b) Why is this group not considered a “natural grouping”?

For a) here is the paraphyletic group: https://imgur.com/yYEq8Bd - the taxa is still "Bat-SL-CoV" ?

For b) It is not considered a natural grouping since it doesn't include all the descendants of the single common ancestor.

3.)  (a) Identify a polyphyletic group on the tree.  Name the taxa in that group.
      (b) How is this different from a paraphyletic group?

For a) here is the polyphyletic group: https://imgur.com/0ufL8Ix - the taxa again is "Bat-SL-CoV" ?

For b) . It is different from the paraphyletic in that it includes unrelated taxa and the taxa are derived from more than one common evolutionary ancestor.

4.)  (a) What is the outgroup in this tree?
      (b) Why are outgroups important (i.e. what kind of information do we get from the outgroup)?

For a) here is the outgroup: https://imgur.com/QEagWCE

For b) Outgroup is used as a point of reference for the construction of ingroups. Thus it makes the phylogeny rooted. Having a rooted phylogeny is important because it helps in determining the polarity of character change or the sequence of character change. Thus the choice of outgroup is essential for understanding the evolution of the phylogeny.

5.)  (a) Which of these two taxa is Human betacoronavirus (MERS-CoV) (JX869059) from Saudi Arabia more closely related to?  Betacoronavirus Germany (marked in yellow) or EF065509 from Guangdong?
      (b) If you were working in this lab that generated this phylogenetic tree and your next step is to develop vaccine based on strains from the animal reservoir of COVID-19 which animal would you be looking for?

For a) It is more closely related to Betacoronavirus Germany (marked in yellow) since we cover the least distance while tracing back to this strain.

For b) If I were working in this lab that generated this phylogenetic tree and my next step is to develop vaccine based on strains from the animal reservoir of COVID-19 I would look for bats.

I think my explanations are good but just not too sure about taxa. Thanks in advance!