The Mount Everest Base Camp Trek
If you begin at Lukla the hike will cover about 75 miles (120km) and you'll lose and gain about 10,000 feet (3000m) in altitude. If you hike at the recommended pace you'll spend about 8 days on the way up and 3-4 on the way down.
Accommodation and Eating
There's no need to camp during the hike if you don't want to. Every village has plenty of trekker's lodges, which usually charge $2-4 per night for a room. However, they impose a high fine ($10+) if you eat outside the lodge. This doesn't mean you can't go out to buy snacks, but they will expect you to have dinner and breakfast there. Meals get more expensive the farther you go up the mountain as yaks and porters must carry nearly all the food to the lodges. A hearty plate of fried noodles would run around $3-4, pancakes around $2-3, hot chocolate around $1-2.
There are also numerous provision shops in villages along the trail where you can buy crackers, cookies, candy bars, sugary drink mixes, soap and other toiletries, and a few other common items that you might need. Expect them to be about 2-4x more expensive than they would be in Kathmandu.
Villages are fairly common at lower elevations, so you'll pass through a few where you can take rest stops during the day's hike. Not so for the 3-4 days when you're near base camp, where the few hamlets like Pangboche and Gorak Shep stay in operation only to accommodate trekkers.
In total, $15-20 per day should cover food and lodging pretty well.
While the trek may seem easier than you expected, don't necessarily let the same optimism run into your expectations about toilet facilities. Heating water is difficult on the mountains, so lodges charge between $2-5 for a hot shower. Cold showers are free, and you'll find they aren't so bad if you work up your body heat by shadow boxing while you're in there.
Quite a few lodges have western-style toilets, but it's likely that you'll end up squatting at some point on the trip. You'll need your own toilet paper, which you can buy at many points along the trail.
The Trekking Routine
Most trekkers get up around 7 AM to have breakfast and hike in the morning soon after the sun rises. You'll usually hike for only 4-5 hours per day because you must limit how fast you ascend the mountain. This leaves you with a surprising amount of free time and few modern means of entertainment.
You can find internet access at small cafes all the way up to Gorak Shep, which is the final village before Everest Base Camp. However, it gets quite expensive at higher elevations (around 25 cents/minute). Most trekkers read, nap and fraternize with other hikers in the lodge to pass the afternoons and evenings before heading to bed around 9PM, when the lodge owners generally let the fire go out.
The Importance of Going Slowly - The Danger of Altitude Sickness
It's important to resist the urge to push on to the next village on the map, despite the advice of your guidebook. You may feel fine after the morning's hike, but even though you could easily reach the next town before sundown you run the risk of becoming seriously and perhaps fatally ill. Going up slowly allows your body to acclimatize, which generally means that the air pressure in the cavities inside your head equalizes with the air pressure outside. Going slowly minimizes your chance of suffering altitude sickness. You can learn more about altitude sickness here.