AI was wondering how far in advance can I bake a cake? Once its baked how should I store it so it says fresh? How far in advance can I decorate it? Sorry, I know, a lot of questions! ! Any advice would be greatly appreciated! !

You can bake your cake several months in advance if you freeze it after it's been baked.  Just put a brown paper bag around the cake to absorb freezer odors.  I don't recommend freezing a cake for several months, though, but a few weeks in the freezer is fine.

If you bake a cake fresh and don't plan to freeze it, 2- 3 days is my max.  One day to bake, one day to frost and one day to decorate.  For a customer, I will bake a cake one week in advance, freeze it and then decorate it the day before I deliver it.

Once baked, to store a fresh cake, wrap it in plastic wrap until you are ready to decorate it.

If it's frozen, wrap in plastic and then in the paper bag.

For clients, unless it's a last minute cake order, I bake cakes a week in advance all the time. Like Norasmom said, you can do it months in advance if wrapped well (I personally wouldn't do it that far in advance, but it can be done). If you torte your cakes, I would level and torte them, then place a piece of saran wrap or wax paper in between the cut layers. 

I would then wrap them in plastic wrap, place a cake board underneath each layer for support so it freezes flat, and wrap again (essentially double wrapping them). For extended time (over a month), I'd do a final wrapping of foil over the plastic wrap. 

Unless it's fresh fruit, I like to fill and ice the cake 2 days before and refrigerate. Then I decorate the night before and keep refrigerated again (even fondant covered cakes) until delivery/pick-up.

That being said, I always freeze my cakes, even if it's for the next day because the freezing keeps it fresher than the fridge and the freezing of the moisture in the cake improves the texture of the cake. 

I have baked 1,000s of cakes - many of them in advanced.  Like when I have 2, 3 or even 4 weddings in one weekend.  If I didn't bake ahead and freeze I would never be able to accomplish the tasks.

Many, many couples choose to save their top tier - at least it used to be a tradition!  That means the cake is frozen for 1 full year:)  My own daughter moved out of the country and didn't return for over 2 yrs yet they still choose to keep their top tier and did eat a bite of it when they returned (the cr ch frosting had soured some).

To specifically answer your ?:

A cake that is made 'fresh' should be in your hands only 2-3 days.  A cake will remain 'fresh' up to 5 days so you want the customer to get it as quickly as possible.

To bake ahead, just let the baked cake cool enough to handle and wrap it well for storage.  How it is wrapped will depend on how long you intend to freeze it.  For up to 1 week I just pop it into a plastic bag.  Anything longer then wrap in plastic wrap, then put into a cake box which is then put into a large plastic bag.  This will keep a cake fresh for up to 2 or 3 months.

If you (or anyone reading this) are afraid to freeze ahead, do take the time to try it.  Next time you make a cake, make a bit more batter so you can make a small (a lg cupcake or 6"?) cake to 'play'/experiment with.  Be sure to mark the size, flavor and date it was baked so you will know months later what it is.  I think yhou will be pleasantly surprised.

..........Aileen said:  place a cake board underneath each layer for support so it freezes flat............

Oh yes - forgot to mention this:)

AI'm wondering the same. Can I fill it and crumb coat it let's say Friday for a Sunday event? And put the fondant on Saturday? Do I leave it out the whole time?

..........Can I fill it and crumb coat it let's say Friday for a Sunday event? And put the fondant on Saturday? Do I leave it out the whole time?...............

Yes, yes, & maybe :)

You can bake say on Thursday, fill and crumb on Friday.  It's best not to leave it out but really depends on your climate.  Hot, humid weather = freezing it.  Then Sat remove from fzr & let thaw - length of time depends on the size of the cake but usually about 1-2 hrs at room temp should do for anything 12" & under - before putting on the fondant. 

Remember, a cake for a customer should be no more than 2 days old before the customer gets it so the customer have 2-3 days to use it up.

AI have an event that I'm making a cake for in Sunday. Right now I'm baking all the cakes, going to fill them and crumb coat with buttercream. Was thinking of putting them all in the fridge today, cover with fondant tomorrow and serve on Sunday.

Most household refrigerators will dry out a cake - even if it is wrapped in plastic.  It's best to freeze them, even just overnight.