Shopify Customisation

I am looking for a bit of customisation on my Shopify store.

https://sale-posters.co.uk/collections/sale-posters

On my collection pages I want to include a small sub line of text under the product name with dimensions of the posters.

Also I want the add the cart button brought up beside the Quantity and the products spaced out a little more.

I have attached a rough mock - two on left are current and 2 on right is new design to give you an idea.