Change my data Type (string / integer) (and create a model question)

I have a mongoDB database that i connected to metabase. And i want to do some graph with sum or average data but all my data are "string" so metabase doesn't count it to sum it and i can't change my data type in mongoDB(don't have the right to do it).
Do you know if there is a way to change a column which data is set a string to integer ?
PS: And while i am asking, is there a way to make a model of a question that i can re use just by changing the table ?
like this

Unfortunately that’s still not possible unless you use the api

Can you give me more details about the api ? (i should have created two différent topic for the two questions mb, your answer was about the first or the second question?)

Try opening the browser dev tools (network tab) when you create or save a question and see how your browser interacts with the api, it’s easier than reading the docs