[Plugins: WooCommerce] How to fix image problems (size& category)

Hi,

I am currently trying to add products to my woocommerce shop but have a couple of issues. Would really appreciate any assistance you could provide.

1st issue
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When you go to the shop on my website all the images are different sizes. The width seems constant but the images have varying heights and I was wondering how I set the image size so all the images are the same size?

2nd issue
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When you go to the shop on my website the products are displayed in categories.However, although all the categories are displaying none of them have an image. Therefore, I was wondering how I assign an image for each category.

Thanks in advance for any assistance you can offer.

Regards

Cas40