How to get there?
From the US west coast, a stopover in the midwest or the east coast will make your trip hours longer (but may be cheaper), because you won't get as much savings from a Great-Circle routing. A stopover in Europe is often better, unless it's a long layover. So pay attention to total travel time, and decide whether you'd rather spend more time on a plane or more time wandering around an airport with time to kill, if that's the tradeoff you have.
How to pay for stuff?
Use your ATM card to get cash, or use a credit card. In Europe, I usually get cash for about half of my purchases, using a credit card for the rest, and using the purchases near the end to balance it out. Tourist places are usually kind enough to let you pay cash for some and use a credit card for the rest, to use up your spare cash. I recommend doing this to get rid of all the money you don't want as souvenirs, unless you or a friend will use it in the near future. We spent enough time in Europe that I got a Capital One credit card before leaving; unlike most credit cards,they do not add a surcharge for foreign transactions. ATMs are as common in Western Europe as in the US (and easy enough to find in touristy places in India). Let your bank and/or credit card issuer know in advance when & where you are traveling, and ask about any daily limits; otherwise, they will often decline foreign transactions due to concerns of possible fraud. When you are worried about daily limits, wait at least a full 24 hours between ATM withdrawls, so you (hopefully) don't have to worry about time zone issues.
Personally, I don't find it that useful to do straight currency conversions, except when I'm worried about running into my bank's daily limit or trying to decide whether it's cheaper to wait and buy something back at home. It's more useful to get a general feel for each country's prices in their own currency. When I lived in Norway, I often divided by 10 to get a rough estimate on whether something was a good value for Norway, even though the exchange rate was around 6-7. However, in some countries, you'll find that particular things seem to be even more expensive than everything else (eating out at some place with tables/chairs in Iceland, hotels in Norway, ...) while other things will be cheaper.
I need power!
Lots of electronics have power supplies that are explicitly labeled something like (110-240V, 50-60Hz). This is good, as US power is 120V 60Hz, while Europe is 220-240V 50Hz (at least all of Western Europe). Most places around the world are in that range. So all you need is a plug to do the mechanical conversion. Apparently there are different mechanical plug standards in Europe; I've never sorted out which is which, but whatever I have always seems to work, except in the UK.
Personally, I just don't bring things that aren't labeled "110-240V, 50-60Hz", I just figure out how to do without. (It's why I stopped using electric razors!) However, you can also buy special converters for this.
Wikitravel seems to have a good writeup on all of this.
For buying them, if you want more than one, consider buying them online, as you can get them cheaper there, you just have to pay for shipping. You can also get them at Radio Shack, and probably most luggage stores.
I don't know the language!
Your experience will vary. In Western Europe, I've found that the larger the population of a country, the less likely individuals are to speak good English. I'm told that in France, it's not unusual for people to refuse to speak English unless you at least try to speak French first. In Scandinavia, it's rare to encounter someone under 50 who doesn't speak English, except in rural non-tourist places. In Germany, people are often willing to use English, but it isn't as good.
The most common phrases I seem to use are "please", "thank you", "excuse me", and "do you speak English?" unless I'm venturing to use Norwegian (which I know a fair bit of) or German (which I have distant memories of learning in high school).
Where to eat?
That will vary. One general recommendation I have is to go ahead and get the hotel breakfast. It's often a little overpriced, but it's really convenient and leaves you with one fewer choice to make in planning your day.
What to pack?
Um, I don't know. I use the guide to packing in Rick Steves' Europe Through the Back Door 2009. (I generally like his guide books, but note that, unlike guides like the Lonely Planet, they make no attempt to be comprehensive, they only cover his personal favorite hotels/sites/towns/cities.)