To answer your question, yes there are definitely opinions out there. Here are mine:
1) Definitely lower the ledger board 6". No matter how well the threshold is sealed under the door, water will get in. The adjacent flashing is not the issue. It's the fact that melting snow and ice will drain to the low point which at times will be your threshold, and at times may even be the door bottom.
2) Check and see how the ledger is fastened. Lag bolts are only 'ok'. It should be carriage bolted to your bond, and your bond should be well secured from subfloor nailing, plate nails, and some toenails. If your floor joists run perpendicular to the bond they should have some toenails in them, not just end nails.
3) Use a 'drop girder' of triple 2 x 10s with 8' spacing on your posts, and holding it back 2' from the overall width of your deck, and flush with the bottom of your joists.
4) If you have access to #1 treated lumber, it's a much better product than some of what's out there and costs about the same. Use it for your structure.
5) Crown your header and all your joists with the crown up. If you do go with Trex or another composite, set your joists on 12" centers, and make sure similar crowns go together. Otherwise your deck won't be flat, it'll snake all over the place.
6) Check into 'Ipe' for your decking, it's about the same as Cedar in pricing but a superior decking material.
7) If that's vinyl siding, remove enough courses to get up at 18" or so, then ice shield the wall, and lap it down onto your ledger board.
8) Staple strips of tarpaper to the top edges of your framing. It'll help to seal out water which lays there for days after rain, and stays between the underside of your deck board and the top of the joist, leading to premature failure.
9) There are several products you can use to 'blind fasten' the decking. It's a lot of extra work, but give it some thought. 'Deckmaster' is a good product.
10) Plan out your posts and railing ahead of time. It'll be a lot easier to set your posts prior to running all the decking than waiting 'til after the entire deck is down.
11) Use three stringers for your stairs, and seal the cuts on the stringers before installing the treads. Use one 2 x 6 along with one 2 x 8 for each tread, and a 1" overhang over your plumb cut, and keep your rise under 8 1/2". It will make a much more comfortable stair than two, 2 x 6s for treads, and tall rises, which are more common. You don't need risers. Everything will drain better without them.