It's whatever your company gives you. Talk to your HR department.
Personally, I have an education benefit, that I can use for courses, if I have pre-approval from the company.
When I worked for a previous company, there was a fund that I could use for books, and they had the ame deal on courses, but did such a bad job of explaining it (telling me that I would only be reimbursed for college credit courses if I got a high enough grade, but neglected to mention that I had to get approval in advance before I even *started* the course, so I ended up getting shafted for my first two semesters).
When I wored for a university, I could take courses for a nominal fee, but due to sloppy paperwork, when the university sold off their certificate classes, they didn't have records of the fact that I was a staff member at the time, so I ended up with months of dealing with a collections agency that was sent after me.
Almost all of them had other limits on using the benefits -- for example, some companies require you to be an employee for 12 months before you can take classes; others will require you to pay back the benefit if you quit within some time frame after taking the class (12-18 months is typical, but I've heard of places that do 24 or 36 months) . One of the companies required me to explain how the course was relevant to my job.
You should also talk to your manager -- there are cases where some courses might make it more likely for you to get a promotion or a better raise when annual reviews come around. (and it'd be a good idea to get it in writing, if you're thinking about paying out of pocket for it).
As for the paying for time at the classes -- I've only had it when it was either a workshop attached to a conference, so only 1-2 days, or training that I was specifically sent to at the request of the company (typically 3-5 days, although there was one case where it was two weeks back-to-back, but it was 2 classes). I've also had them pay my time to take certification tests, when it was required as part of my job.
I have never had a company pay my time when I was taking college level classes that I elected to go to, even if it was related to my job. They did, however, let me take off in the middle of the day to go to classes at the local university, and were otherwise understanding when I shifted my schedule around.