Questions about size, rivers and a swamp.

[Xeziares]

Hi everyon! I'm not very experienced in map making, but I am eager to learn. So I have some questions and I really hope you can help me out a bit.

Here's the outlines of my map, and a quick sketch of the mountains and rivers:


First I'd like to ask you about the size. How big do you think this should be? (like how many km/miles long from the top to the end?)
Would it be possible to put at least 4 kingdoms in this piece of land?
What I think myself, is that my mountains are perhaps too big, and that will make the land look smaller.
Do you think, if I would make the mountains smaller, that his piece of land could be a continent?

Second, I'm note sure about the rivers. Besides mountains, what can be a source for rivers? And if you let a river come from a mountain, does it have to be a snowy mountain?
I'm not sure if my rivers are realistic enough...

Last but not least: I want a swamp.
The kind of swamp as in, for example, "Pirates of the Caribbean 2" where Tia Dalma lives.
But where can you place a swamp? Must it be near the ocean, or not, or must it be near a river. Can it be in the middle of the land, or does it need to be surrounded by water? I tried to google it, but I couldn't get a clear answer. (Perhaps it's my english, idk)

Hope you guys can help me out. And feel free to give critiques, I need them!

oh, here's btw a picture of my map's "climate":

The yellow is like desert, the green is with grass and woods, and the top is a bit emptier.. I'm not sure how to call it, it's like dead land..

Greetings,

Xeziares. (Just call me X if that's easier, haha)