, the prefixes are stuff like 'tbl_' for tables, 'vw_' for views and 'sp_' for procedures (the last one in itself is a bad practise. If you absolutely must prefix, use usp for procedures), and stuff like fltAccountBalance, bitReceiveNewsLetter etc. I have only superficially played around with the flixon generator, but I'd think that "tbh" should be fine. If not, you can always alter the templates it uses.
The dicsuccion between ID and CODE is a different subject. My guess is Flixon uses the "ID" suffix to determine where a relationship exists, purely to be able to create the proper lookups in the generated code. You most likely can also change this to use "Code" rather than ID, but I'd strongly advise you not to. ID is short for Identifier. Code, on the other hand, could mean a lot of things. An ID used in a database schema, by definition, is a meaningless code, whose only "function" it is to uniquely identify an entity. A "code", could have meaning in it. I know, semantics, but still ;)
If I remember correctly, if you want to add a few columns with Flixon, and you know for a fact that the rest of the generated code is equal to the code you currently have, I'd say the best option you have it just to completely replace the existing files. However, if you're like me, and you built custom hacks everywhere into your code, you're most likely better off creating fake copies of your tables and generating the code based on those. You then have to merge the generated code with the existing code.
I wish I could help out more, but my knowledge of Flixon is rather limited atm. Hope this helped a bit anyway. If you want, I can have another go at the flixon stuff, and see if I was talking crap in this post.