Ok, rispondo per gli USA, anche se ti consiglierei di sentire un avvocato
1) Scordatelo. Non ti fanno entrare neanche per sbaglio negli USA.
Citando il sito dell' INA
"
Immigration to the United States of America is governed by the Immigration and Nationality Act (INA). According to s. 221(d) of the INA, all individuals applying for an immigrant visa must submit to a mental and physical medical examination before the visa is issued. [...] Under INA §212(a)(4), an applicant who is likely to become a public charge at any time is excludable. The INS looks at the totality of circumstances in making its determination including their age, capacity to earn a living, health, family circumstances, employment history and whether or not they have ever received public assistance. Most immigrants must submit an affidavit of support as evidence that they will not become a public charge."
Oltretutto, i contributi della Social Security per i disabili possono essere percepiti solo se sei nato cittadino USA o se hai versato almeno 5 anni di tasse negli ultimi 10 anni. Contando inoltre che un visto te lo danno solo se hai un lavoro prima anche solo di pensare di partire*, lascia perdere.