1)Should i make a party entirely by me (using modem create or something)
The game was designed in such a way, that to have the best gaming experience, you make one PC and 'hire' 5 NPCs. A personally made party will lack the NPC interaction and romances, but it will enable to create funky roleplay parties like Robin Hood and his Merry Men.
2)do multi classed characters get to top level in both classes? because if they do shouldnt they be way better then the normal class because the kits dont seem that great...
The Xp is split between the classes in a multiclassed character.
3)Same thing but Dual class
The Xp is also split between the classes, and you can never level up in the original class, after you dual.
4)Which are better, Sorcerers or mages?
By far the Sorcerer, but until you learn the basic rules of spellcasting, a Mage is your better bet. Blindly making a Sorcerer leads to much angst, trust me on this. Get a better feel on how magic works in the game first, then ponder making a Sorcerer.
5)Are specialist mages worth it? you lose a whole school...
Yes, especially the Conjurer and the Necromancer. These two are generally considered the best two.
6)The shapeshifter druid looks pretty cool, being able to be a greater werewolf at level 13? Is shapeshifter good?
Yes, in a party.
7)If i create all my own characters (At least for beggining) What would be a good party combo
A Paladin kit( not a plain Paladin), a Conjurer, a Berserker dualled to a Cleric at level 9, an Assassin, an Archer and a multiclassed Cleric/Mage.
This is one of many ideal combinations. There are many others.