No, you can still get PS's, just write down the ones you are interested, the apprx times/days you would like and call. You probably will not be able to get specific times you want at the park restaurants and the really popular resort ones. Just be flexible. If I were you, I would at least get a few, you can always cancel them if you can't make it to them.
As to your being a 'newbie' to WDW, I would suggest the following, take a break, away from the parks, during the day. I cannot stress this enough. If you do this, it will make your stay MUCH more enjoyable (especially in august, with the heat and the crowds).
It also makes dinner and breakfast PS's easier to make because you don't have to cater them around which park you are visiting as strictly. (because it gives you an excuse to take a break)
For example: for a dinner PS: (no matter where it is located)
You can visit a park in the morning, leave for a break at your resort (freshen up, take a nap, etc), go to your dinner PS and then visit another park (or the same one) again in the evening.
For a breakfast PS: (if it is in a park):
Go to that park, go to your PS for breakfast, enjoy that park and leave in the afternoon when the crowds/heat get overwhelming...relax and go back to that park or try another in the evening....
It may SEEM like too much bother (and traveling back and forth)...but TRUST me...it really is better to go back and forth than to stay in one place ALL day.
Hope you have a great trip, the BC is really nice (we stayed at the YC our last trip...loved it, especially stormalong bay!)