Its not an easy deck to play so I don't think you are going to get the full feel of the deck if you only played it once.
- Loam is primarily for post board games, and dredging, but Dakmor+Rifstone means that Loam is always alive, even main deck. You can boost the number of Dakmors if you want to make sure you can loam game 1.
- Bridge from Below doesn't really increase speed, it just increases resilience under special circumstances. So if you aren't getting turn 2 Griselbrand here, then I don't think you are getting turn 2 Griselbrand in most dredge builds. The only dredge builds that even semi-consistently do that are full turbo with Fatestitchers and that version usually struggles post board. Most Dredge decks are turn 3/4 decks, this holds for this one as well.
- I disagree. The lack of reliance on Bridge from Below and lack of needing to win in combat improves the match up dramatically, but if you are looking for a "mirror breaker", its Failure to Comply. That blocks any opposing Dread Return, essentially time walking the game. Leyline is just not good against any non-mirror match. If you want to pick your deck based on the chance someone else will play a suboptimal list than so be it, but it seems like a poor choice if the goal is to win a tournament.
- The deck is not designed to maximize game 1 win %. That is already a very easy win if you play the deck well. You need to maximize game 2/3 win %'s in my opinion. Tormod's Crypts are at an all time high, and Grudge is a must. I've since upped to 4.
If you have a decklist then I could make specific recommendations. Loam can usually replace some other dredgers, and rifstone can usually replace some other lands.