Whoa... spell failure is back?
No, that's not at all what I said. The spell failure system of Morrowind is not in the game. The spell fails to cast if you attempt to cast it farther than your maximum summoning range. There's no percentage chance. While charging, it shows your magicka being drained for the cost of the spell, but if the spell fails to cast, you immediately get that magicka refunded.
I knew it had to be easy. My familiar was a wolf/fox. is everyone have the same or is it random?
It's always a wolf. If you attack it four times it will attack you back, and it does have a small chance of giving you the Rockjoint disease (-25% melee damage) like other wolves.
Note: you get conjuration experience whenever you cast a conjuration spell, but also whenever your conjured creatures take damage. A fun way to level up an attacking skill and conjuration at once is to summon something and beat it to death. Because they start with Summon Familiar, bretons have a unique chance among races to level up several skills while still in the tutorial area.