How many visa types can a potential EB-5 investor apply for?

There is no limit as to the types of petitions you may file as long as they have legitimate basis and are nonfrivolous. While your I-130 or I-526 is pending, you will have to extend your current E-2 status to remain in lawful immigration status in the United States to be able to adjust your status to that of a permanent resident. A pending immigrant petition may affect renewal of your nonimmigrant E-2 status.

An E-2 status can be converted into an EB-5 case. In addition, there is no legal restriction on how many immigrant petitions can be filed.

There is no limit to the number of U.S. immigration routes. You can renew your E-2 visa. However, your sibling-based green card application may affect your EB-5 application, since we do not know your priority date of your sibling-based green card application.

Generally, there is no limit to the number of visa categories you can apply for. Yes, you have to extend the E-2 if the EB-5 is still pending.

Yes, there is a limit. You may progress from the E-2 status to an EB-5 application. The EB-5 will lead to a change of status, to wit a permanent residence; a sibling application would result in the same outcome, i.e. permanent residency. USCIS may not look with favor on two applications for the same permanent residency.

It may be possible to have multiple immigrant petitions pending at one time, as long as you are filing legitimate petitions for each. While these petitions are pending, you still have to maintain proper, legal U.S. status (that is, renew the E-2), or else leave the United States and go through the consulate once one of the immigrant petitions is approved.

You can apply for as many immigrant visas as you are eligible for and one will not impact the other. Once an EB-5 immigrant petition has been filed, you will have a very tough time renewing the E-2 visa (or perhaps even entering on the E-2 visa), but if you are in valid status in the country while the immigrant petition is pending, that should be fine.