i. Exchange traded funds (ETFs) equally distributed among the US stock fund, a US bond fund, an international stock fund, and an international bond fund. This is because ETFs provides diversification and low expenses.
ii.The perfect time to start saving is as soon as you have a full-time job. If the employer has a tax deferred investment plan, and if the employer matches some of your investment then you'll be ready to get extra benefits.
iii. I'd put my investments in ETFs equally distributed among a US stock fund, an international fund, a US bond fund and an international bond fund. This reduces expenses through diversification.