ur english very hard to understand
i'll try to answer u...

Cement, is for u to "glue" ur gundam parts 2gether to hold it permanently...

Pla-plate is just like a piece of paper but it is plastic and there are different "thickness"..

ur last question, duno wat u r trying to say

Bro actually if u want a really cheap compressor u can go for this :  Tamiya Basic Air Compressor

It comes with a single action air brush and is very cheap... i got mine for only RM 200... thats about the price of your Mastergrade kit... so why not get one of this instead ? 

Its amazing for its price, by the way... powered by a 7.2v ni-cad battery... lasts around 15 minutes continuously.... ( honestly i have NEVER turned it on longer than that... and as soon as i stop painting, i swtiched it off... )

Theres no pressure regulator or anything else... its basically just " fill the cup and spray, rinse and repeat "... great for airbrush newbies like me. 

It saves ur trouble of getting other airbrush parts...  and its really light and portable.

U can check on ebay for this airbrush..... just my suggestion.. 

I'm new here and I'm from Vietnam.

I want to ask you guys that how can you guys erase the original paint?
Well, simply put, my country is lacking a lot of stuff. MG model is about ten, nearly 5 or 6 model SD, no topcoat, ****ing expensive paint, ****ing expensive tool . So may be some mixing stuff will do the trick. Thnx ^^

If it's for AB(Air Brush) then make sure it's smooth. u can test it using the ab gun wether it's too "watery" or too " "muddy". For AB, u nid it smooth....

For hand painting, make sure not too "watery"... if not the paint wont stick when u paint on it...
sorry, do kno how to use words.. hehe

can paint without using thinner?

sorry about the frist question i mean can I replace super glue instead of cement? also is it a must to use cement on the gundam model?

about compound I still quite confuse and also it comes several types like basic,finish and etc. which one should I get? and how much should I put the compound on the model?

1. Cement, super glue, white glue, epoxy glu, etc, are all the same purpose, they stick two things together. the difference is the chemical compound of them. As a result, different glue is used on different material or surface.

cement is actually not a glue, it's a chemical that melts the plastic (PS) which in the end makes things much easier for a modeler. U can even use those gum for shoes, but it will give u lots of problem. So your answer is, no, it's not a "must" to use cement; but it ll be easier.
2. Compound, is basically like sand paper, and it's in liquid form. For really fine sanding, due to the stiffness of paper (sandpaper), it's very hard to control extremely fine sanding. Therefore many use compound to sand those places with such requirement. Eg, extremely glossy surface.

if u understand the nature of the material, u can use it any way u see fit. For example, some people do use compound to sand off nip marks...... of course u dont do it when u have a nip mark that is big like an elephant. trim it as small as possible, untill you side cutter, sand paper, n pen knife cannot do the job anymore, try compound it a little.

if same color maybe 2-3 bottles.... like sazabi or shinanju....