lets say that I have a familliar, in this case a hamster. After I bind it I decide I want to give it some abilities and makes it able to sprout wings and mental communication as well as turning its fur to steel. All this are possible in RAW.
But I would like to have it be able to spit lightning bolts. Is that possible ? Or can it only be Personal (touch) range spells in the bond?
Your best bet is probably to use the Muto Animal Guideline "Give an animal a "magical" ability, such as the ability to breathe fire (requires a requisite for the ability)." That way you're affecting the familiar, so it should be enchantable into the bond. The guideline is base 25, though.
You can also give you familiar a magic item that shoots lightning (like teeny collar). That would require only CrAu rather than MuAn(Cr,Au)
Note that bond powers are generally under the control of the other end of the bond. So the familiar would only spit lightning when you say so, not when it wants to. It sort of puts a curb on a lot of stuff you'd put in your familiar, which is why giving them magic items is useful.
By a strict reading of the RAW it would be possible, as stated, only by Muto-ing the familiar into something that can spit lightning bolts. That said, at least one example in the corebook contradicts the RAW - a power that shrouds the familiar in flame, so that the flame burns everything touching the familiar but not the familiar itself. You could argue that something that shrouds the familiar's nose in lightning, which the familiar can then sneeze against those it dislikes, is not really that different.
:mrgreen:
An empowered hamster familiar that sneezes lightning - is it named "Peek-Achoo!"? 
There's a few other options as well - one from the core book and two from RoP:M.
Firstly, you could invent the effect not as a familiar bond power but as a spell. Familiars themselves are immune to warping thanks to their having a might score. Whether or not this is easier is going to depend on your magical focus (if any).
Secondly, you could go and find a few rooks of vis and feed it to your familiar (as per RoP:M) to get it to develop a greater power that lets it spit lightning bolts. Depending on the might of your familiar this might get expensive, but has the up-side of not requiring an epic lab total, just epic amounts of vis, as in probably more than 10x the vis cost of empowering the bond.
Thirdly, you could take advantage of the fact that familiars don't suffer a might-based xp penalty and go and find a magical creature that already has the ability to spit lighting bolts and is willing to teach your familiar how to do it. Of course, finding such a creature and convincing it to teach your familar is probably going to involve some pretty big quests, which makes this the 'go adventuring!' option. This might result in finding texts written by such a creature (perhaps even another magus' familiar), but note that the power must be one innate to the creature and not one that is part of a familiar bond.
Note that with the RoPM options your familiar might end up with a magical inferiority as well, giving both a strong similarity to initiation quests.
Splitting hairs, here, but Familiars still suffer Might based penalties for Transformations.
RoP:Magic Errata:
"Advancement (p. 51-2): On page 52, add the following sentence at the end of the first section, immediately before the Transformation header. "Finally, as stated in ArM5 (page 105), magic creatures bound as familiars to Hermetic magi learn in the same way as humans, and retain those Abilities if the familiar bond is broken." "
Core book:
"Familiars can learn Abilities in the same way as humans."
Familiars can learn Abilities as humans do, not Transformations. The Errata is before the Transformation section, and both sections reference Abilities only.
Fair enough. Shame, because having a magus go on a quest to find and convince a magical being would be a perfectly good story. I'd probably let it slide anyway, because story.