That usually do not take long for americans. If you have kids you can do it when they're small so they are ready for university when they come of age.
I knew students back in Mexico preparing for their Abitur exams for Germany at the end of high school (in all fairness, they were coming from bilingual private high school, which is a extreme luxury in Mexico, but still way below what college tuition in the U.S. looks like at most research universities...).
As for the salary, I can only say a German computer science graduate being offered a real programming job would probably laugh at anything below 45K, and is looking at around 50K. After tax this comes to around 30K/year (don't quote me on this number), which will be enough to live if you're single, for more costs of living you can check numbeo.com
Um, the post I was responding to mentioned getting residency in Europe in order to take advantage of the university system, so....