Single phase from 3 phase generator
Your 1st question, yes and common up earth and neutral, BUT are you qualified to do such work?

2nd question. If you measured the voltage between two hot wires you won't get 220 volts. You should see about 190 volts because line voltage is phase voltage (110 volts) x square root of 3 (1.732).

Question 3. I'm thinking about this one because potentially (possible apt word)  appliances on one phase may cone into contact with appliances on a different phase and this would cause sparks if not properly insulated. Also, when you are old and infirm and you get an electrician round to fix or modify your AC distribution or ring mains he may be in for a big shock!