I picked a difficult set to start with, as there are still many cards outside of the top twenty that will see plenty of Standard play
Choice is a wonderful thing, but many beginners appreciate simplicity when it comes to learning a new TCG
Similarly, a creature whose toughness is doubled gets +0/+X, where X is its toughness as the effect begins to apply
This is usually fine in Commander and can pay off after being in play a few turns (be careful though as some players may remove these)
Firstly, the land you find comes into play untapped if its a basic land or a shock land
You can sometimes "splash" a third, playing two colors as your base and a couple powerful cards or additional costs of another color, but I'd really focus on the two colors you want here