I am having issues identifying how to change the size of my product title, could someone please point me in the right direction?
It is huge on a mobile device and I would love to be able to fix this.
I'm also not keen on the fact that the path to this item is shown above the title and if anyone knows how to remove this it would be greatly appreciated.
I think that default window is pretty narrow (outdated) but I do see what you mean. I don't see any native way to change it from Theme>Change Fonts, but the product page on the live mobile site does not look bad. I don't have an overly large or wide device, and everything fits nicely on the screen.
As far as the breadcrumbs go... currently it is a feature request to remove them or make them optional. Although, I will say, that even if they don't look aesthetically pleasing to you, I bet they are super practical and useable by your customers. I personally utilize these handy links when I'm shopping online all the time. Just something to consider. 
That said, there is a post here on community where a user was able to figure out where to delete this in the html/css area. If you are not comfortable with editing the code, I highly advise against using this method. Editing the html/css info will put your site on a "custom" theme. You may receive limited support if your theme is not on a standard Weebly theme. 😕 However, a lot of these edits can be placed as overrides in the Settings>SEO>Header section of the editor. If you place the code here it will not put you on a custom theme. Ideally you want to stick to edits that work in this section.
There's a couple overrides in this thread you can try out. If those don't work, another user might have another suggestion for you. https://community.weebly.com/t5/eCommerce/Controlling-the-MANDATORY-Categories-page-of-cascaded-pare...
