Those are immature though, so they look fine to me. They've even still got their seed shells clinging to the tops. They'll get much bigger and then start flopping over.

If it were me, and I were wanting them to be a permanent thing, I would break them into small bunches. The number depending on how much chives you want to grow. And that's it, really. The bunches will get increasingly larger as the bulbs divide themselves. And if you plant them in good-quality potting mix, you won't need to fertilise until after you've harvested.

They look fine to me. I never separated mine. My pot of chives looks similar to yours. I don't see the need to separate. It is a clumping plant. When you do cut some stems to use them, please cut them all the way to the base of the plant. If you don't the rest of the stem will just turn yellow and die.

Chives is indeed a clumping plant but it increases its clump by new bulbs growing. As Sophie says the chives in the photo are actually a pot full of many seedlings i.e. tens of individual plants rather than a single plant clump. I would divide it in due course and give each division a pot of its own. Also that pot is labelled biodegradable so it would probably start to break down eventually. Healthy chives are perennial and should grow for years if happy.

Your chives are whispy because they're not in plenty of bright light. They thrive in the full outdoor sun.

As far as not needing to divide them: Chives really benefit from division. It's good practice to do so every few years (when there's about 10 bulbs, split the plant into 2 5 bulbed ones). It just keeps the plant growing and healthy. If you don't have the space for it, just dry out the half you don't put back for later use.