Before my 1st trip to WDW, I was scared that I wouldn't know how to do Fastpass....I shouldn't have worried. You'll get it!
1. Where do we get it? If a particular ride (usually the popular ones) offers Fastpass, there will be a 'bank' of machines somewhere near the ride's entrance.
2. Does one Fast pass work for the whole family (4)? No, each person MUST have their own Fastpass to get on a ride.
3. How do we use it? Very simple...we usually designate a 'runner' (which is normally myself, as I: a. know how to navigate the parks better than my family, and b. am the fastest runner/walker! ). After you've designated a runner, have that runner hold ALL the tickets; they will take the WHOLE family's tickets, insert them into the machine one at a time, and out spits a FASTPASS for each ticket inserted.
BEFORE you do this, look ABOVE the Fastpass machines. There will be a sign, indicating what TIME the current tickets spitting out will be good for! It could possibly be SEVERAL hours later; decide if you want to get one for THIS particular ride! The reason - you are limited to only so many Fastpasses at a time!!
4. Will it really be needed for last week of April? It's not supposed to be really crowded. This is your personal preference. I've been in January, when it wasn't crowded at all, but liked having a Fastpass in my hand "just in case". Plus, it helped me really understand the system for future visits. If you get to a park early in the morning, and it doesn't appear crowded, don't be misled. I would still grab a Fastpass for a popular ride, ride it Standby, and then use the Fastpass for a later ride. Crowd attendance can change very quickly!!! What was an empty park at 9:30 am can be packed to the wazzoo at 11:00 am!!!