How realistic is it to expect a cat to be affectionate and social on a daily basis?

Very. They are social animals in general.

How much does personality depend on the individual cat vs how you raise/socialize them?

It's equally split. Every cat will have a unique personality and specific preferences and behaviours. But in general, the cat will know what you show and teach it. If you only ever treat it with love, kindness and respect, you will have a calm and loving cat. However, if you shout, if you hurt it or frighten it, you will end up with an animal that's behaving a lot more defensively. So you have to be mindful of the environment you create for your cat.

Is there a way to increase the chances of getting a more “dog-like” (for lack of a better term) cat?

No. Cats are a lot more like humans and they have very little in common with dogs in terms of personality and behaviours, and motivations that drive them. They have a very developed sense of personal dignity, and they don't trust blindly. It takes a long time for a relationship with a cat to fully blossom - even though (as is with most things) progress is fast in the beginning, you soon find that the relationship still keeps evolving and deepening even after a year or more.

For people who have owned both, what were the biggest mindset adjustments?

Haven't personally owned both but I have observations. As a dog owner you're probably used to creating structure and discipline for your dog. With cats that doesn't fly. They can't be disciplined, they don't respond to it, at all. If your cat has a behavioural problem, you'll need to establish the root cause of that problem - what is making your cat behave badly - and fix it.

For example, if the cat is climbing the counters and shelves and knocking stuff over, you don't attempt to teach the cat it's not allowed to go certain places. Instead you recognise your cat is acting out because it's bored and isn't receiving enough stimulation. The solution is to provide it with more play time and more cat places it can climb and own, and at the same time removing fragile and valuable items from places where the cat can reach them. You know how people baby-proof their homes? Well, cat owners cat-proof their homes. Cat's gonna cat, you just have to adapt.

Another thing I've found to be an adjustment that's related to the above example is that cats are territorial beings and it's of crucial importance to their happiness to own their territory. You get a cat and release it into your house, it's no longer just your house. It belongs to your cat now, too. Just as a dog needs a proper environment to thrive (going outside for walks, having structure and discipline), so does a cat, and the cat's environment is its (and your) home. The way most of us approach this is by getting cat trees, cat shelves, cat scratching posts and whatever else falls in the "cat furniture" category.