To create "nonstandard combination of Races and Classes" is simple!

Let me share it with you, cause I have just finished it myself too.

You will need to edit the followings:
CharBaseInfo.dbc file
PlayercreateInfo.DB file (in Mysql)
Player_levelstats.DB file (in Mysql)
Player_createinfo_spell.DB (in Mysql)
Player_create_action.DB (in Mysql)

If you edit these , there should not be any problem.
Short description: (Write me privately to explain it step by step if u don't understand something!)
1.CharBaseInfo.DBC determines Races/Class Combos

2.Player_create_info does the same but in Mysql database and you can set different spawn location with the coordinates and the map id.

3. Player_levelstats determines which stat of the nonstandard class should get level by level. If u accept my advice just simply copy the already existing templates so it could be faster.

4. Player_createinfo_spell - this is the point when it gets a bit more complicated.
Your custom new class wont have the basic abilities (racials etc.) it should already have. (Arcane Affinity etc.)
So u have to determine in this DB what to have. But take a good look, cause here you have to use ClassMask and Racemask IDs not Class and Race IDs (so the bit value form - for example : bloodelf which race id is 10 , racemask here is 512!) and if u want to allow for multiple races the same ability/spell or whatever you have sum them!
Don't forget that for example if u create Bloodelf Warrior, like I just did, and u edit player_createinfo_spell to provide Belf Warrior the Arcane Torrent Ability that ability wont give u rage! (you have to create or edit the spell to provide you rage, cause the Player_createinfo_spell is using different spells for all specific classes related to their source of power.

5. Playercreate_action is just about what spells should be placed out to your actionbars when u log in! (like auto attack, arcane torrent, and 2 class spells i think)
This is not that important just an option but we are working to get it perfect!

I hope it helped you!

Keep me Updated about your progress!
Trust me, it should take like 1 hour maximum to get these done and working!

ID   Value   Name
1   1   Human
2   2   Orc
3   4   Dwarf
4   8   Night Elf
5   16   Undead
6   32   Tauren
7   64   Gnome
8   128   Troll
9   256   Goblin (4.x)
10   512   Blood Elf
11   1024   Draenei
12   2048   Fel Orc
13   4096   Naga
14   8192   Broken
15   16384   Skeleton
16   32768   Vrykul
17   65536   Tuskarr
18   131072   Forest Troll
19   262144   Taunka
20   524288   Northrend Skeleton
21   1048576   Ice Troll
22   2097152   Worgen (4.x)
24   8388608   Pandaren Neutral (5.x)
25   16777216   Pandaren Alliance (5.x)
26   33554432   Pandaren Horde (5.x)

ID   Value   Name
1   1   Warrior
2   2   Paladin
3   4   Hunter
4   8   Rogue
5   16   Priest
6   32   Death Knight (3.x)
7   64   Shaman
8   128   Mage
9   256   Warlock
10   512   Monk (5.x)
11   1024   Druid
12   2048   Demon Hunter (7.x)

I have written a whole monologue about asking for help in spell editing, but the site crashed and I lost all my writings so far! So I start again with a quick fully problem oriented shorter version!

I would like to edit spells , but I dont know what the MISC VALUE A B C means/connected to/related to/working method etc.
And I feel like I have been surfing the net sinces ages to find information about what I am facing, how I could understand the working method...yet I did not find any potential "explaining" posts or threads or whatever!
So I registered here, " I put my faith in the Light"  , and I can just hope that among this forum members there is someone who figures it out, and will be so kind and helpful to share these information with me!
I do apologize if I have written my post/topic at a very wrong section! Please forgive me, won't happen again!
Thank you in advance!

Good Gaming!
Hanzo!