The Elder Scrolls IV- Enchanting weapon and more questions

I have read few guides of both and none have got an answer i am looking for so i will ask here.
1) On enchanting weapons there is a thunder sign (how much you can use for e.g 40 fire damage) at the moment i have 0(85)
and a thunder sign next to it how do i make (85) go up so i can put more into fire damage etc?

2)Items in oblivion have say 2800 charges and 44 uses but when i make a weapon it has 1600 charge and 21 uses is there away to make
my uses of the weapon go up? (even if it involves charges going up ie gems?)

3) How can i get better armour/weapons to find? i am level 18 and still have full steel with a bit of dwaren and blackwood armour?
Not just better armour but get full dwaren orcish anythink?

4) If i use forty magikca on weapons and i have 208 magikca but whislt wearing the armour its know 352, when i buy a spell
that requires 308 magikca will i still be able to use it even though my orignal magikca is 208 but i am wearing the armour making it 352?

Well my only guess for number 2 then is i can have a grand soul gem and put past 1600 soul points in it? otherwise it must be because of how strong it is?