Stage Presence would mean that all enemies within your burst or aura range would be affected by Entangle, no rolling required. This is the same for all spells like Cure, where you would normally pick one ally, it could affect all allies within your burst/aura. The only exception is spells that explicitly state they are not affected by stage presence.
For Mosh Pit, spell attacks essentially mean you can do a basic attack and cast a spell with the same action, but the spell is not a burst or aura, and affects the target of your basic attack, which can depend on what your basic attack’s range is. For Microphone, that’s a single-target melee attack unless you also have the Soundwaves quirk. (It’s one of Gun’s traits, but now I realize I didn’t put a page reference for it!)
As an example, you both roll your typical basic attack against someone, and regardless of any hits, you can also cast a spell against that target. If it’s a spell that can normally target multiple entities, it would still only affect the target of your basic attack. (However, if your basic attack can hit multiple entities & the spell is single target, it would have the reverse effect and hit all of those targets)
Hope this helps!