How do I know if my wheel bearing is bad or if it's both my bearing and hub?
 

Having the rumbling/cracking sound on my left driver side wheel. Terrible noise when I'm driving, even at slow speeds. The wheel has some play, it's a bad bearing obviously. When getting it replaced will they automatically replace the hub too? If it's just the bearing I'd like to do that only, save myself some cash. Is it standard to do both together?

Also, how bad is it to drive on it? Been driving on it for a few weeks now, and possibly have a 100 mile trip to do depending on how safe it is to drive? I hear the wheel can lock up.

You have to pull it apart to know if it's damaged the hub but if it's sounding that bad it probably has.

I wouldn't drive on it any more than you absolutely have to. Especially on a trip.

It's all one assembly, you replace the bearing, the hub is with it, you replace the hub the bearing is with it.

If its that bad, I'm sure the hub is also bad. Replace both.

You can replace just the bearing, $10-$49, or entire assembly $25-$96 (RockAuto)
The hub isn't necessarily bad as when the bearings go, the outer race can be unaffected, but replacing just the bearing will usually require a press/machine shop.
Replace the entire assembly and be done with the job.

As far as driving, I wouldn't take a long trip as it's been bad for quite a while for the wheel
to have play. Not saying you won't make the trip successfully, it's just questionable.

That's cool, I didn't realize you could get the assembly already pressed together. That's definitely the way to go for most people who don't have access to the necessary tools.

I've always bought new bearings and pressed the old ones out only to find that the hub is bad 1/2 of the time.

Let's be clear in that the front hub won't be pressed into the bearing, it's just that they will all be new.
You'll still need get the old out and the new in.

Now I see what went wrong here, you didn't indicate front or rear, rear hub comes with bearing, fronts come separately, sorry.

You shouldn't be sorry as I should have been more explicit in my details for either front/rear, rather than a mixture of each, or I had better read more closely next time.