(Translated from Hebrew)
Davening with a live stream of a Minyan via the Internet:

In the present reality of the Corona Virus, it is worthwhile to recommend broadcasting tefilot via Zoom for the whole country and the whole world, as there is a significant benefit to this being done. This should be done in accordance with the following details:

1.    It is reasonable to assume that there is great worth to this, even greater than Davening alone at the time that the tzibbur is davening. (But, of course, this is not actually considered tefillah b’tzibbur)

2.    Answering Amen: It appears that one can answer Amen
3.    Answering Devarim Shebikdusha: There is uncertainty regarding answering Devarim Shebikdusha. On the one hand, even a mehitza (partition) does not interrupt the connection between B’nei Yisrael and their Father in Heaven. On the other hand, it’s possible that to answer Devrim Shebikdusha one would need to hear the real voices of those saying them. Therefore, the recommendation is to ideally respond with the te’amim (i.e. trop or cantillation marks) even for the verses from kedusha or the 13 Middot HaRahamim. 
(It seems that one would be able to answer Kaddish regularly)
(The introductory paragraph of kedusha, ‘’Nakdishakh,’’ [or Nekadesh for Nusach Ashkenaz] is really only meant for the Chazzan to say and therefore, fundamentally, the Chazzan should be the only one saying it. However, most congregations have had the custom to say it as well. In our situation, it is best not to say it, for one is davening alone.)
4.    Answering Kaddish: It is not proper to say Kaddish when one is davening alone. It’s too difficult to assume that he is really b’tzibbur when he is so far from the minyan. Nonetheless, it is recommended that [the one who wants to say kaddish] should listen carefully to Kaddish and fulfill his obligation via Shome’a K’Oneh, and know that responding Amen to a Berakha is greater than making the blessing yourself. One may also hire someone for pay to say Kaddish for him. One may also learn for the Neshamah of the deceased as there is great worth to such a practice.
5.    Where there is no minyan in one place: If even upon gathering via the internet, there still is no minyan, it is difficult to say that this is considered a Tefilla B’tzidbbur. (As we have seen, even with regards to the law of mehitza, Tosfot wrote that ten men need to be present in the same place [and not interrupted by a partition]). Therefore, one cannot say Kaddish or Kedusha. Nevertheless, [even the gathering of individuals via the internet] has a certain degree of worth as it unites all of Israel in their approach to davening (similar to what Rishonim wrote with regards to the Nusach of Davening, which functions to unite all of Israel before their Father in Heaven—the same would apply here.)
6.    Vatikin: Even when one prays individually, there is a significance to davening Vatikin. 
7.    Davening on Porches (Mirpasot) and the like: There is a dispute whether individuals on different porches can join together to form a minyan. In our circumstances, we can rely on the lenient opinion and a minyan can be formed if the individuals can see one another. It is permissible to daven with a microphone so that, while only 10 men can see each other, the rest of the minyan can listen and answer. Others can also answer via live stream on Zoom and the like.