If you are instructed to cast a spell with overload "without paying its mana cost," you can't choose to pay its overload cost instead
Illustrated by Tyler Walpole Standard Not Legal Alchemy Not Legal Pioneer Not Legal Historic Legal Modern Not Legal Brawl Legal Legacy Not Legal Comp
As for the latter, it digs you into your deck for a free creature each turn, so hand size isnt an issue
If you're told to proliferate, you choose any number of players and/or permanents that have one or more counters on them
Outlaws of Thunder Junction (OTJ) #85 Illustrated by David Palumbo Magic: The Gathering, MTG Company: Wizards of the Coast Series: Outlaws of Thunder Junction Item Type: Single Card Brand: Magic The Gathering Release Date: April 19, 2024 UPC: Stock #: 475949 Our Guarantees to You, Our Valued Customer
However, Jump-start changes the calculus, because Direct Current isnt one bad spell, but two flexible spells