It costs inconsequentially more to host large files, sure, but the cost is usually on the consumer vis-à-vis their ISP to stream larger files.

Are both ports otherwise equal specs-wise?

No laptops are meant to be used on your lap. A better name for them would be portable PC, but that isn’t as catchy.

Because despite their name, laptops are meant to be placed on a hard flat surface when in use - NOT on your lap, a pillow, etc. They have little rubber feet that allow just enough room for the hot air to escape, and when placed on your lap the air gets trapped. Manufacturers warn about the effects of the hot air on your lap for extended periods of time.