Assassins are included among outlaws, so outlaw payoffs like Olivia, Opulent Outlaw and Vihaan, Goldwaker also work as assassin payoffs
Centering must be around 70%/30% to 75%/25% or better on the front and 90%/10% or better on the back
PMJ Silhouette Gloom of the Sundown Lands Articles Head #16 Blaziken looks kinda decent, either ramp with Magby or just manually attach t1 and you're off to the races t2
Other than that you can and should play more lands than normal (40+) so you can consistently hit every land drop - this will help to keep some ramp spells for after you played Omnath - because drawing lands isn't really that bad in any stage of the game anyway thanks to your commander
As an Uncommon, Pikachu is fairly easy to find, with over 100 available listings on TCGplayer at the time of writing
This premium card was released as a part of the expansion Fusion Strike, which has more chase cards than you can count