For "direct to you," you absolutely need a business account, since in this mode, you're the one selling directly to buyers, and PayPal requires a business account to accept credit card payments.
(EDIT: One correction: if I remember correctly, Itch uses Stripe to process credit card payments, so it might be possible to use a personal account on "direct to you".)

If you use the "Collected by Itch.io" mode, it doesn't matter, as PayPal allows you to have occasional sales or receive money from Itch to your personal account.

Personal advice: if you create a business account, you must have a legally registered business in your country. If PayPal detects any suspicious activity, they may request documentation proving your business is legitimate, and without this documentation, you risk having your account closed.

You can see the fees here:

https://www.paypal.com/business/paypal-business-fees

But basically, you'll get around a 5% commission on each sale (regardless of the Itch method you use). If you use "Collected by Itch.io," when Itch transfers the money to you, there's an additional fee, which I believe has a maximum value of $5 USD.

If you want to transfer money from your PayPal account to your bank, there's another fee, and if the currency used is different, PayPal's exchange rate will always be unfavorable.