I've called before to ask if it's crowded that day. They've had space even an hour before a busy holiday time. I wouldn't worry about it on a normal day.
It's helpful I'm sure but I think you can go without
Not typically, but sometimes on big holiday weekends.
Agree with above. Easy to make reservations by calling them. Because Boeing employees use this service the lot can fill up. They give reservations simply on the honor system- i.e. they put you on a list but no pre pay is necessary. Also if you travel frequently call ahead for a corporate rate which is significant.
Not required but a good idea for holidays. There no extra cost for reservations. If you have AAA you can get a discount.
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