Looks like you have a majority of your plan already worked out.
1. Just open a Vanguard account and put money in it? You can dollar-cost average if you're more comfortable with that, or some split between the two, but studies show that time in the market is better on average than waiting. There is a risk that you'll put it in the market and the market will drop significantly in the near future, but that's just the nature of the market.
2. Both splits are good for long-term investing, which is what you'll be doing. You have enough assets to consider diversifying a little more, but you don't have to. If you're going to buy a house within 5 years, you might want to put some aside in a short-term investment.
3. Your asset allocation should be across all of your assets, with funds placed according to tax efficiency:
https://www.bogleheads.org/wiki/Principles_of_tax-efficient_fund_placement . With a simple stock/bond split, this would mean putting all of your bond investment inside your tax-deferred accounts. Rebalancing can be a pain if you diversify more, but it's worth it.
4. Some mix of shielding your assets from FAFSA in your home and retirement accounts, 529, and qualified IRA withdraws. This is a pretty big topic, so spend some time poking around on this forum and elsewhere.
5. Timing the market usually doesn't work. You will always risk losing a big chunk of money, but you have to get into the market at some point. Might as well take the risk and maximize your time in the market.
6. Do you mean buying a primary residence, or investing in real estate?