I'm from Washington and have done all my pre-req's up here for the BSN program, (hangin' out in the Texas forum because I'll be moving down there in August-can't wait!!!!); so I won't have all the answers, but hope I can get you headed in the right direction.
A credit hour is how classes are measured. In the quarter system, it reflects how many hours you spend in class a week; although I have never taken classes in a semester system, so it might be different. For instance, if your anatomy class is 5 credits, you can expect to be in class for 5 hours a week (typically 1 hour per day), and anticipate studying an average of 2 hours per week for every credit hour the class is (ie, 10 hours of anatomy study time per week.) This formula was just the one used by my most recent university, so it may vary from school to school and is of course highly dependent on the individual.
I'm guessing with an MSN program you will need all the usual nursing pre-req's, which should be listed in detail on the specific program websites. Starting from scratch, it typically takes 1-2 years of full-time study. A "full-time" load in the quarter system is usually 12-18 credits, or 3-4 classes. If you don't have a science background, or have extensive commitments outside of school, I wouldn't recommend more than 2-3 classes to start, erroring on the side of caution to ensure better grades which will increase your chance of acceptance if the programs you are applying to are competetive. You will know your own capabilities though. You should be able to calculate the amount of time it will take at the cc based on credit hours, but it also depends on class availability (some classes are only offered one or two quarters during the year.) Sequence courses (such as Chemistry) will also sometimes lengthen the total amount of time it takes to get through the pre-req's, so you might consider starting with those so you don't have to put off applying because you need to finish out the series. (This again coming from the experience of having to do so!) Best to plan ahead and map it out to make sure one quarter isn't going to be overloaded and another going to be a piece of cake.
As a graduate of the MSN programs I am familiar with, you will come out as an APN, and may also have a speciality if you choose to go that route. Again though, each program is different and will usually describe the level you will be licenced at upon graduation on their website or in printed program material. If available, you might also find info sessions helpful to answer questions (usually held once every couple of weeks to once every couple of months depending on the program.) Some are great, others not so helpful, but it's worth a shot if you have lots of questions or very program specific questions that aren't answered on the website.
Hope this helps, let me know if there is anything else I might be able to answer for you. Good luck!