Only One Payment Method

-- url of the page with the problem -- : www.mdperformance.com/
-- HikaShop version -- : 2.3.5
-- Joomla version -- : 3.4.0

1. If we only have one payment option do we need to add the payment method in the checkout workflow?1.
2. Do we need to display it?

Thanks Jerome,

1. Do you know the css file I would modify and the css code I would use?

2. We have "Auto select default shipping and payment methods" set to yes.

Thanks.