PFS is definitely a great way to get experience with the system. Depending on how your particular metro operates, you might need to stop in at a game store and ask around to figure out if there are any closer PFS games. Even if you aren't able to play, it can be a good idea to go to a game just to observe and chat with more experienced players. We had a lively discussion last night about reach weapons at my local shop that clarified a lot of different things for some experienced players.
Regarding some of your earlier points about lost time calculating DCs and such, here are some recommendations:
-If it's a common situation, write down the modifiers. Power Attack, for example, can have its own line on your Attack section of the character sheet. For a lot of different sheets, you'll find that there are areas specifically designed for tracking things like spell DCs that are on the spell page.
-Print off relevant pages that you need to reference. If an ability is too long to write down, print it off. If you use spells, use a spell card generator, like Perram's Spellbook.
-Take some time before the session to re-read anything you're hazy on and to refamiliarize yourself with your character. I recommend 5-10 minutes even if you're comfortable with what the character does. This helps train your eyes to look at the right section of the character sheet and can remind you of modifiers you might otherwise forget.