Do a search for "CCB" on the forum and you'll get plenty of info and warnings about those. This has been covered many times. Most of the CCBs have "Italian" sounding names.
I'd suggest looking for a decent used bass instead. CCBs are not worth the heartache no matter how cheap they are at first. They are not well made, come apart easily, and don't sound good.
Some good starter bass "brands" are: Shen, Christopher, Engelhardt, Strunal, and Eastman.
Not all Chinese basses are crap, (Shen, Christopher & Eastman are Chinese made). Strunal is Czech made, and Engelhardts are USA made. There are other good ones too, do some looking around and play some basses at shops if you can. Any brand new bass will need a setup to make it playable (string height lowered, etc.) and better strings put on. The "shipping strings" on most new basses are like bailing wire.
Oh, and yes, 3/4 is the standard most commonly played size. One last thing, check out
www.bassesonline.com - they are liquidating a whole warehouse full of nice German & Czech basses for incredible prices. The Eberle laminate would be a great choice and they do a setup for you, so the basses are playable when you get them.
Hope this is helpful, be sure to read the newbie links here also.
Getting a good bass will mean you will be more likely to stick with it. The double bass may be one of the most challenging instruments to learn, but it's also the most rewarding.