new Requirements to travel Europe- ETIAS?

If you travel in a group is this necessary

Yes, travelling in a group won't change the requirements. Although no start date has been set yet.

why exactly will this be needed in addition to a passport?

Because the EU has decided that it will needed.

There are multiple other threads on the forum on this topic.

Currently ETIAS is not active, and has no confirmed start date. It is delayed by several years. There will be lots of news about it when and if it comes on stream, rather than idle speculation.

Why do you believe that travelling in a group would make any difference?

why exactly will this be needed in addition to a passport?

For the same reasons as visitors to the United States, Australia and many other countries require supplementary authorisation- whether it is termed an ETIAS (or similar) or a Visa.

Don't worry too much about it, if and when it is implemented, your airline will be one of the first to notify you, as they likely will be required to check that you have done it.

In practice, it will be minimal effort, fill out a form, answer some questions, complete payment of a few euros, and hit send. You will get some type of approval (very likely) in anywhere from minutes to a couple days.

Why are they doing this? They are essentially asking you questions that you could be asked at the border, and if needed, they could go off and do some more investigation if there is an issue. The up side is that, likely, this will pave the way for more automation at immigration, simple e-gates-scan your passport and go, since they already have your info.

It should not cause many people problems, the biggest thing might be some type of felony conviction in your past that might throw up a flag, or if you did something silly like overstaying your welcome in one of the Schengen countries.

It is nothing to worry about and is merely the European version of our own ESTA that folks have to get to visit the US from visa-waiver countries. It's not implemented yet so it is simply best to follow the official website --
https://travel-europe.europa.eu/etias_en
https://travel-europe.europa.eu/etias/what-etias_en

The UK will eventually have their own electronic travel authorization, or ETA, implemented at a future date --
https://www.gov.uk/guidance/electronic-travel-authorisation-eta

I know a few people who might worry. Here are the questions:

ETIAS Application Questions
The ETIAS application form requires you to provide the following information:

Your full name (surname, first name).
Date of birth.
Place of birth.
Country of birth.
Your nationality.
Your parent’s first name.
The type, number, and country of issue of your travel document.
Home address or country of residence.
Email address and phone number.
Education (primary, secondary, higher, or none).
Current occupation, etc.
After proving your personal data, you will be required to answer the following questions:

Whether you have been convicted of any criminal offense over the previous 10 years or of terrorist offenses (20 years). If yes, when and in which country?
Whether you have stayed in a specific war or conflict zone over the previous 10 years and the reason for your stay.
Whether you have been the subject of any decision that required you to leave the territory of a Member State.
*If you answer Yes to any of the questions above, you will be required to provide answers to an additional set of questions.