there's lots of threads on particles... if i could be bothered looking i could quote the answer to everyone of your questions from somebody else. but i can't so, here we go.
wa
used commonly in statements
um, i don't think that's the exact definition, but it's true. it's often called the "topic marker".
ga
used to draw attention to the subject of the sentence
true again, it's often called the "subject marker". be careful though, because ga is quite a versitile particle, and often pops up as something other than the subject marker.
ha
I've never seen this in basic textbooks.. how is it used?
this is the same as wa (see above). the hiragana character for the particle 'wa' is written as the hiragana character for 'ha'. don't ask me why. even though it is written as ha, it is read as wa.
wo
This is new to me, but I see it quite frequently. The textbooks I've read seem to use O instead, like in 'Sushi o kudasai'. Are they interchangeable?
yes, they are interchangeable. they are the same thing even. the w is usually silent (the w can be pronounced if wanting to be extra polite. also often pronounced in songs).
ni
location marker
de
usage marker
yeah, fair enough. it can be more complicated than that though, but that's enough for now i think.
e
location marker again.. I see this in textbooks, for example 'kyoto e iketai' but seldom see it elsewhere. Is it interchangeable with ni? How is it pronounced? Yee, or eh?
this is like the above wa/ha example. it is written with the hiragana character 'he', but read as 'e'. so be careful, you may see it written as he. it is pronounced as an "eh" sound, but if you are not familiar with the basic japanese pronunciation, i suggest you find someone who can teach you. as for the meaning of e, it's just like ni, often used to express the action of going to a place (such as in kyoto e ikitai).
And while we're at it, what're the differences between desu ka and desu ga?
well ka is essentially a question mark. so desu ka is asking a question. ga in this case means but. it is not the "subject marker".
this might get a bit confusing - here's an example in english.
"i was going to go to the shops, but it's raining." translating into pseudo-japanese would be "(i was going to go to the shops) ga, (it's raining)". but in japanese often things are implied, so if it's clearly raining, you could just cut that bit out. in other words "(i was going to go to shops) ga..." is ok. therefore ending a sentence in desu ga is also ok