3) PPF is not for everyone.
Only resident Indians are permitted to open a PPF account.
If you are a non-resident India, or NRI, you will not be eligible to open an account. The same for a person of Indian origin, or PIO.
However, a resident who becomes an NRI during the account's tenure can continue prescribing to the PPF account though the money in this account is maintained strictly on a non-repatriation basis. But he cannot extend the account on maturity. Resident Indians can extend the tenure of an account by a block of 5 years on maturity.
If you are thinking of migrating and leaving the country, it is pointless to open such an account. Unless of course it matures when you are still a resident Indian and can claim all the money when it completes its tenure.