Can I control a planeswalker with Confiscate? Is a planeswalker a permanent that can be the target of Confiscate?
Yes. All cards and tokens on the battlefield are permanents, including Planeswalkers.
110.1. A permanent is a card or token on the battlefield. A permanent remains on the battlefield indefinitely. A card or token becomes a permanent as it enters the battlefield and it stops being a permanent as it’s moved to another zone by an effect or rule.
110.4. There are five permanent types: artifact, creature, enchantment, land, and planeswalker. Instant and sorcery cards can’t enter the battlefield and thus can’t be permanents. Some tribal cards can enter the battlefield and some can’t, depending on their other card types. See section 3, “Card Types.”