For me, Harmison looked most dangerous at Edgbaston and Lords, and Flintoff at Lords and Headingley. In fact, at Lords he was pretty much unplayable, and sent down one of the best spells of the series. Harmison as you say likes uneven bounce, but he also looked good when it was seaming at Lords. Jones will be much better when it's seaming, I think, and Hoggard obviously needs swing. Giles won't be a major factor in the tests, I don't think. The Australians will clearly target him, and if he's anything other than a 30+ average stock bowler I'll be shocked, and England need to be bowling Australia out regularly for sub-400 totals to win this series. The best bet, is a situation like Lords where they can get wicket which has some grass on it and seams a bit early on, and hopefully win the toss and send Australia in with it overcast and bowl them out for 250 or less.
What England definately don't want, is a flat wicket which breaks up and turns later in the match, like the last couple of ODI wickets. If there are five wickets like that and the weather stays good, Australia are quite capable of winning all the tests for mine. If it's seaming the whole way, it could go either way and though I'd still pick an Australian win I would expect it to be a close series.