You are riding the pacific coast, right?

1. on the pacific coast, you won't have to go more than 40 miles between towns, from my memory. Usually it's more like 30. Maybe 50 once or twice. You don't have to carry more than one full day of meals, ever, although occasionally you do need to buy tomorrow's breakfast at today's lunch. I was fine with 3 bike water bottles. If you have the book/map you will know in advance.

2. There are camp sites all the way, you don't have to wild camp at all. Or at least, that used to be the case. There are state park campsites, many of which have coin-operated showers. Some of the CA state parks have been impacted by budget cuts, so you might need to do some research on closures. Most state parks have a hiker/biker camp site, which is cheaper and available to people like you who come in w/o a car. Sometimes you need to use an RV Park if the state parks are far apart, but not too often.

The biggest danger both in and outside of developed camp sites, is raccoons, which want your food and are very clever and aggressive about getting it, and poison oak, which you should just learn to identify so you don't walk thru it. The official camp sites have food storage boxes, where you can put your food so the raccoons don't get it.

Camping right on the beach is usually not allowed.

3. Good time of year for it, stable weather, days start getting short. 2 months is a very long time for that trip, I did Bellingham, WA to Redwood City (a few miles south of San Francisco) in 21 days, and it takes another 8-ish riding days to get to LA. So add a few rest days, a few shorter days, and you might be able to stretch it out to 2 months.

Even if there is a La Nina or El Nino, that time of year is usually stable and dry. End of October, might start seeing a storm or two, but I wouldn't sweat it.

4. There is a book - Bicycling the Pacific Coast, by Kirkendall & Spring - and a map (the one you linked from www.adventurecycling.org )- if you want to know where the camping and towns are in advance. Makes it very easy. Either of those is fine, the biggest difference is whether you want to be able to see the info while riding, get the map and put it in a map pocket on top of your handlebar bag. I used the book for the pacific coast and the maps for other routes, both are good, I think it's worth it, others may not.

There is also a free bike touring map of Oregon that you can pick up probably at a visitor center or bike shop.

Have a great trip!