1. Mutual funds in all my accounts - tax advantaged or taxable. I don't plan on trading daily or even monthly, and they seem to be the most recommended for a buy and hold strategy.
2. I don't consider any of it technically available for just anything. I figure my taxable account will be the first stage of my early retirement funding, but that's about it.
3. Yes, I based my account allocations on the bogleheads' recommendations. All of my bonds and REIT funds are in tax-advantaged accounts (IRA and 401K) and my main chunk of stock mutual funds are in my taxable (a total stock mutual fund is actually all that I have in my taxable).
http://www.bogleheads.org/wiki/Principles_of_tax-efficient_fund_placement 4. I don't tap the taxable. I have a separate savings account for upcoming expenses not associated with retirement. I would not invest money that I would need in a year or two. Barring a serious emergency, that money is being left to grow as much as possible.
5. (you have two #4s!) Um. Sort of? The husband and I have our own checking accounts (joint) that we use to pay bills and the like. One is my primary, one is his. We have a savings account (earns crap interest) that is used as a short term bucket as a basic emergency fund. So at any given time, there is about 6 months worth of expenses between all three of these accounts. That's the amount my husband feels comfortable with, so that's what we hold. If we were saving up for something big ticket like a house, then we probably would locate a high yield savings account to park that money, but we don't have anything like that on the horizon currently.
If you're definitely planning a home purchase, then I'd say that if you do invest money earmarked for a downpayment, keep in mind that due to the day to day fluctuations, short term (under 2 years) investing is a bit more risky.