Drow and Nagaji are not animals - or do you mean Drow druids having different familiarities?
Seen & touched may not be an easy rule to work with either. How do you know what the druid has done before joining a campaign? Has he been down to a zoo and touched a tiger?
Familiar with means exactly what it sounds like.
You certainly would have had to see it, probably not touched it. But you must know a good amount about the creature.
For instance, if a druid had never seen or knew anything about dinosaurs, it wouldn't make sense for him to wildshape into one. However, I think if a druid has a knowledge (nature) score high enough to identify the creature they should definitely count as being familiar.
As it is, the rules aren't really clear and it's left up to GM discretion. Personally, i think your rule of "and touched" goes to far. It is a rough restriction since once your in the game you as the GM will determine what creatures he encounters. The player will have little to no control over what he would like to turn into, and that sucks. Personally I think if you want to implement something make the player make a Know(nature) check against the DC to identify the creature to be able to turn into it.
Druids aren't animorphs, they shouldn't be restricted as such.
For plants or elementals if you must make a requirement knowledge(nature) and knowledge(planes) as appropriate for the creature type.
In this context, I would say "familiar" means "well-acquainted" or "thoroughly conversant" (see definition 2 here). A druid has to know quite a lot about an animal in order to be able to turn into it. I wouldn't consider seeing and touching an animal either necessary or sufficient for the use of wild shape. The druid really needs to understand the chosen animal's behaviour and nature in order to become it - but this knowledge wouldn't necessarily have to be acquired first-hand, so Knowledge (nature) checks would be appropriate in some cases. This is a situation where GM ruling, as well as co-operation between the GM and the player, is really required.
Personally I think if you want to implement something make the player make a Know(nature) check against the DC to identify the creature to be able to turn into it.
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For plants or elementals if you must make a requirement knowledge(nature) and knowledge(planes) as appropriate for the creature type.
Perfect.
He's a Druid from Orv, so becoming a Bear is actually sillier than becoming a Megaraptor.
Keep in mind that by level 3, if he puts a few ranks into the knowledges he's going to be able to identify most normal animals by taking 10. DC is just 5+creatures CR.
Also I would have these done ahead of time. Rather then in the middle of the session. IE at the start of the game have him make a knowledge check for a bunch of animals he wants to be able to turn into (make a list). Each time he gains a level, let him repeat for any that he missed.
Considering Knowledge Nature is very powerful in that a druid can identify plants, animals, insects etc. anywhere on the planet with an appropriate check, that limiting a druid's wildshape with cavets like must have seen and touched, somewhat cripples a main class feature.
If the druid can know a creature using the appropriate Knowledge check, then to me it is reasonable that they have "heard of", "seen", "touched" said creature and so can wildshape into it once they meet the usual prerequisites.
If you want to limit the shapes he can take, rather than saying he must be familiar with or have seen/touched the animal, just make him pick 1 form/character level. Those are the only forms he can take when he wild shapes.
That still gives the druid plenty of options (he will have 4 shapes he can take when he first gains wild shape at 4th level), while still limiting what he can turn into. And as the GM, you will know exactly what the druid is capable of. (Also, I would count things like "Earth Elemental" as one shape, instead of forcing him to take Small Earth Elemental, Medium Earth Elemental, Large Earth Elemental, and so on.)
And if the druid is ever unhappy with one of his choices, that is what the Retraining rules are for.
I generally say a druid is familiar with anything from their home region, anything they've personally seen/fought during the campaign, and anything they could identify taking 10 on an appropriate Knowledge check.
Beaten to the punch but as far as I can tell that, or just giving them all knowledge (the rolls really are absurdly easy to make), is how it's supposed to be adjudicated RAW/RAI.
Home region common sense (I.e. unfailable knowedge rolls) + personlly experienced in game + what you can get with knowledge:nature identify rules (though I'm unsure if take 20 is allowable, don't have book w/me at moment to read fine print).
I also toss in whatever S:NA (/S:M) can automatically summon for the players (which should usually fall under unfailable), including elementals (which should definitely be common knowledge as both summon lines at almost all levels have), as simple (probably or almost automatic) spellcraft rolls would reveal all that as well.
Plus I believe you can gain a bonus to the attempts due to aid from others with the skill or resources like libraries with solid information on it.