If you gain an amount of life "for each" of something, that life is gained as one event and Sanguine Bond's ability triggers only once
If the target of Dross Skullbomb's last ability isn't a legal target as the ability tries to resolve (probably because it has left the graveyard), you won't draw a card
But theres only so many places in a Commander deck for sac-draw spells when you look at the limitations of those cards in comparison to these other ones, and those three dont make the cut
Marvel, Kamala Khan Nerd Rage Nezahal, Primal Tide Niv-Mizzet, Visionary Nyssa of Traken Power Without Equal Praetor's Counsel Price of Knowledge Proft's Eidetic Memory Reed Richards, Smartest Man Reliquary Tower Roaring Furnace // Steaming Sauna Roaring Furnace // Steaming Sauna Sea Gate Restoration Spellbook Spirit Water Revival Stairs to Infinity Tamiyo, Seasoned Scholar Tamiyo, the Moon Sage The Great Synthesis The Lux Foundation Library The Magic Mirror The Second Doctor Thought Vessel Tishana, Voice of Thunder Triskaidekaphile Undercity Reaches Venser's Journal Vnwxt, Verbose Host Wisdom of Ages Wizard Class Wrenn and Seven Your Puny Minds Cannot Fathom
(Don't apply Weakness and Resistance for Benched Pokmon.) Mega Skarmory is a personal bet of mine