Hi there,

To remove the reduces opacity from the logo's you can use the following CSS line. Please add it in the CSS textarea of the customizer:

.client-logos img { opacity: 1; }

The only way to automatically make the logo's the same size is to use the native WordPress crop size in your image. By default WordPress created 3 image sizes if you upload a image (thumbnail, medium and large). 

You can use the thumbnail size (150x150pixels) in your image URL after you've uploaded the image with the following:

http://yourdomain.com/path-to-image-150x150.png

If you want to use another size unfortunately you should scale/crop your images manually.

If you have any questions, feel free to ask

You're welcome.

Removing the border and combining it with the previous CSS makes it:

.client-logos img { opacity: 1; border: none; }

The WordPress crop function isn't that great as it will automatically crop the images based on the proportion/size how they're uploaded.  Unfortunately there is not much to edit on the thumbnail. 

If the logos in thumbnail size not as desired I recommend to manually scale them with an image editor.

The logo image is added in the text editor as follow:

<img src="path-to-image.jpg" alt="Insurance 1">

If you want to link the image to a URL you can wrap the img tag within an a tag as follow. Only change the http://link-to-url.com to your URL

<a href="http://link-to-url.com">
    <img src="http://path-to-image.jpg" alt="Insurance 1">
</a>