Hard to tell from the pic. Can you take a pic of one by itself?

In either case, if caterpillars are doing damage, spray with BT K variant -- available at ANY garden center and is organic.

If you see any large ones, you'll have to pick them off. Vy isn't nearly as effective on "older" caterpillars

Here is a link that might be useful: pic of an large tobacco hornworm

Yes, it's a tomato or tobacco hornworm. The most efficient method of control is to inspect your plants carefully for the eggs and the cats and remove them. Don't forget that those big caterpillars hatch from teeny round eggs. If you are only finding them when they get to be huge....you're letting them do a lot of damage in the meantime!

What do the eggs look like? Are they in the soil or on the plant? Will these eat other plants as well?

The moths, Carolina Sphinx and 5 Spotted Hawkmoth, that lay the eggs the become these Hornworms lay them on the plants leaves, both sides. What is often referred to as the Tomato, or Tobacco, Hornworm will munch on any plant in the nightshade family, Tomatoes, Tobacco, Peppers, Potatoes, etc.
Apparently getting good pictures of the eggs on plant leaves is somewhat difficult since there seems to be very few that really show anything.

Shrub, I'd attach a link if I could but I don't know how to do that on my Kindle. Simply type the words ....tobacco hornworm eggs.....into Google and then click on images. There is an enormous number of pictures of the eggs, as well as hatchlings.