A Corriere della Sera article lists the changes made by the new decree. Below is a Google translation (including Si translated as Yup). for many of the FAQs - those missing do not concern visitors.
(Green Pass = Two vaccine shots 'Reinforced' Green Pass = Two shots & a Booster)
From May 1st it will not be necessary to have a green pass. Italy reopens that day. From April 1st, however, the rules change and numerous restrictions fall. This is what the new government decree provides.
1. How long will the masks have to be worn indoors?
Until April 30th.
4. When can you travel on buses and subways without a reinforced green pass?
The obligation falls on April 1st. However, the Ffp2 mask will be mandatory until April 30th.
5. What do you need to get on planes, trains and ships?
From 1 to 30 April the basic green pass will suffice. From May 1st, no certificate will be required and it will no longer be mandatory to wear the Ffp2 mask.
6. Can we sit at a table in a bar or restaurant without a green pass?
From 1 April it will be possible to enter open-air bars and restaurants without a green certificate, while for indoor bars and restaurants it will be necessary to wait until 15 April.
8. Do I need a green pass to enter shops, hairdressers, banks, post offices or public offices?
From 1 April, admission will be unrestricted, you will have to wear a mask.
9. What should someone who has had close contact with a Covid positive person do?
He does not have to comply with the quarantine but has the obligation to wear (indoors or in the presence of crowds) the Ffp2 mask for ten days from the last contact.
13. What do you need to go to the stadium?
From April 1st, the basic green pass and the Ffp2 mask are enough. The capacity is 100%.
14. What are the rules for indoor cinemas, theaters, concert halls and sporting events?
The reinforced green pass is required until April 30th, from May 1st the certificate is no longer required and the obligation to wear the Ffp2 mask is no longer required.
15. Until when will I have to enter health facilities with the reinforced green pass?
Until December 31st.
16. When will we be able to remove the masks?
April 30.
17. Where is the Ffp2 mask mandatory?
Until April 30 to get on buses and subways, airplanes, trains and ships, buses, school buses, cable cars, cable cars and chairlifts, cinema shows, theaters, concert halls, clubs and discos, events and sporting competitions.
18. Do the rules change for playing indoor sports and entering the locker room?
From May 1st there is no need for the green pass for indoor sports and changing rooms.
19. From April 1st, can outdoor sports be practiced without a green pass?
Yup.
21. What are the rules for public celebrations and ceremonies?
From April 1st, admission is free.
22. Also for outdoor festivals, fairs and cultural, social and recreational centers?
Yes, from April 1st the certificate
23. Do you need a green certificate to enter spas, theme and amusement parks?
Only until March 31st.
25. What changes for indoor parties and discos?
Up to 30 April the reinforced green pass is required and a mask must be worn.
28. Do I need a green pass to go to the hotel?
From 1 April, entry to hotels and accommodation facilities is without any limitation.
30. Does the rule also apply to foreign tourists.
There is also no obligation for those arriving from abroad.