If you could write a modern constitution for your country, what amendments would it have?

If I was writing a new constitution, why would it need amendments?

This is a bit of a strange question, because an amendment is just that - an amendment. You don’t list amendments in your first draft of a constitution, you list articles. Amendments are changes made to the constitution after it’s ratified.

None... Because it would have been just written. Amendments are changes/additions to an existing document

USA:
Prison slavery abolished
Elected judges with term limits
Ranked Choice Voting
Bodily autonomy as a right (no banning abortions, gender transitioning, bionics)
Separation of Church and State as the actual law of the land
Add federal referendums, all constitutional amendments are referendums (but amendments still require 75% of the population)
Districts are now no bigger than 50,000 people and they all get a representitive, and all the recognized Amerindian tribes also get their own reps (an agreement was made with the Cherokee for them to get one but it was never fulfilled)
2nd Amendment replaced with something that directly allows federal government to regulate but not ban firearms.
- I’m not big on elected judges. I’d rather keep them appointed so they wouldn’t have to pander to anyone.
  
  Appointed judges already failed to prevent that.
- i wouldn't go with ranked choice voting. all the systems i know of have their own flaws: IRV can have really weird results with more than three candidates, Borda count disproportionately favors the moderate, and the Condorcet method can completely fail to select a winner. instead, what about approval voting, where instead of ranking candidates, you just check as many boxes as you want?
  
  and the Condorcet method can completely fail to select a winner.
  That one's not a flaw. All elections can suffer from ties. Pure Condorcet just makes it obvious when there's a tie (and this is very rare). There are a bunch of Condorcet completion methods for resolving the tie.
- I wonder if the body autonomy thing would work against for you mandating vaccines

Rule 1: Authoritarian shitcunts get the rope
Rule 2: Be excellent to each other (with the exception of rule 1)
Rule 3: Alcohol, Tobacco & Firearms is now a store

I am actually quite happy with Germany's constitution.
- What do you think about the role of your president? Would you get rid of them entirely, or would you give them more powers?
  
  Keep them as they are. I don't think we've ever had this position seriously abused and it's a decent last line of defense ifwhen the brown shit hits the fan again.
  Obviously they can't prevent the public hurting itself again in the long term but they can however at least mitigate that happening to some degree for a little while. That can be enough to smooth over some short-term crisis and might move people to realise their situation a bit better because it'd be a highly, highly exceptional thing for them to step in.
  (For those not in the know: Next to being the representative for the state (does rememberance speeches, shakes hands, etc.), the German president handles some "administrative" stuff in the government without much say and they have the power to effectively stop the legislative until their term is over by refusing to sign new bills.
  The latter has never occured and single bills have only been "vetoed" only 9 times in total. Mostly because of formal issues such as the bill not actually having been approved by the Bundesrat or bills that are obviously in conflict with the Grundgesetz and would get overturned by the judicative immediately.)

A right of water, shelter, food, medical care and schooling. A right to live free of violence, a right of basic equality, for equal justice, a right to privacy, and a right to be forgotten.
- I'd add in a right to connectivity. Not having the internet is a giant disadvantage in today's society.
  But otherwise, your list is top notch!

poverty is prohibited.
- Punishment: heavy fees
  
  In its majestic equality, the law forbids rich and poor alike to sleep under bridges, beg in the streets and steal loaves of bread.
  Anatole France

2a, but simplified for polticians and other toddlers.
The right to keep and bear arms shall not be infringed. No matter how big or small, deadly or not, this is ironclad.
- That amendment lets me purchase nuclear armaments.
  
  I could see an interpretation of this where the government doesn't make it illegal for you to own any weapon but makes selling them illegal. After all, it's not infringing on your right to have them, it just regulates the market for weapons, which isn't forbidden by the letter of the law.
- "No matter how futuristic or advanced guns become" because I'm sick of hearing "bUt ThEsE gUnS wErEn'T iNvEnTeD yEt!"