Darcy:
OK, if you have already done a 20-mile day and are allowing up to a fortnight, there's no reason to skip the road-walking (unless the weather is vile and you have better things to do). The roads aren't particularly busy, but many folk try to squeeze things into a week and on that basis I'd encourage them to cherry-pick the best bits (Dingle to Castlegregory plus Great Blasket IMHO). It sounds like you already have our
Dingle Way book, and most of the answers are in it

If not, you need a copy urgently – from us by Air Mail or via bookstores or from Amazon!

We say it's 8 days walking (see distance table on p10) with a longest day of 18 miles and 4 short days (11/12 miles). We also say that a trip to Great Blasket is (a) unmissable and (b) weather-dependent (pages 27-29). So if you can keep some flexibility, do, but I'd always suggest booking at least the first couple of nights accommodation. Also go in June rather than July if you can (less pressure on accomm, possibly drier).
How to reach Dingle from Dublin is covered on p11 although Shannon and Kerry airports are nearer and I'd have thought you might get a direct flight to Shannon? Easiest method for bag storage is to enlist a B&B in Tralee (or Dublin if going there for other reasons). For bag transfer on the walk, see the operators mentioned on page 62 or refer to this useful
website.
I had great weather, as you can see at our
gallery, and would thoroughly recommend Dingle to anybody. Only regret was not reaching the summit of Mount Brandon half an hour earlier, when the views would have been even clearer; as you see on p51, even the descent was spectacular!
Hope that helps your planning? Please do post your comments once you have been!