Spell Compendium has several "Bite of the X" spells, such as Bite of the Weretiger, that grant enhancement bonuses to physical attributes and give the caster natural attacks. Some include text such as Bite of the Weretiger's "Your hands become claws, granting you two claw attacks..."; does this prevent the caster from wielding weapons, or cause any issues gesturing for the somatic components of spells?
You can cast spells and - likely - use weapons, as per the normal rules of natural attacks
Casting spells requires gestures, but you can do that with appendages other than hands. Even creatures with distinctly non-hand appendages, like a dragon with its claws, can cast spells with somatic components. You do need the appendage to be free and able to gesture, as normal.
The ability to handle weapons is a bit more nebulous, because the spell doesn't specify the exact form of the claws. Most monsters with claws have "hand-like" claws - like the Troll's, for example, which can clearly handle items as a normal hand would. Many beasts have more animalistic claws that can't. Because all humanoid creatures that I know of get hand-like claws, for the rest of the answer I will assume that the Bite of the X-spells give you those as well. If not, you physically can't use weapons (or material components). Unfortunately, since the spell doesn't specify the exact form, the DM will have to make a ruling how exactly the claws work - the only discussion I've found on the matter is one without definitive sources as well, on GiantITP.
The bite and claw attacks are natural weapons, and follow the rules for them. That includes the following rule for manufactured weapons:
Some creatures combine attacks with natural and manufactured weapons when they make a full attack. When they do so, the manufactured weapon attack is considered the primary attack unless the creature’s description indicates otherwise and any natural weapons the creature also uses are considered secondary natural attacks. These secondary attacks do not interfere with the primary attack as attacking with an off-hand weapon does, but they take the usual -5 penalty (or -2 with the Multiattack feat) for such attacks, even if the natural weapon used is normally the creature’s primary natural weapon.
So the Bite and Claw attacks will be made at a -5 (or -2 if you have Multiattack, which some of the spells also grant). Your weapon attacks would work as normal, including iterative attacks. Of course, you can't attack with a claw that you're holding a weapon with, although you can attack with the "off-hand" claw if you're wielding a 1-handed weapon.
As it is written, I'd say you are good to go my friend. Bite of the Weretiger, as our example is written as (emphasis my own):
Your hands become claws, granting you two claw attacks, and your mouth becomes that of a tiger, giving you a bite attack. You can attack with both claws at your full base attack bonus, but your bite attack takes a —2 penalty (as if you had the Multiattack feat).
The spells specifically says you can use the claw and bite attack, but it doesn't say you can't use your claw/hand to wield your weapon instead. The spell also states:
If your base attack bonus is +6 or higher, you do not gain any additional attacks.
So, if your BAB is +6 or lower (unlikely as this is a level 5 Druid/6 Wizard spell), you would be granted an extra claw or bite attack. If the BAB is higher, you can attack with your normal amount of attacks, you just have more kinds of attacks to choose from.
This DM would rule that an appendage needs to choose if it will go natural or weapon attack, then if an appendage has already made its attacks (claw holding a sword), it is done for the round (it's been busy attacking with the sword). The other appendages, including the new bite attack can still be used though.
As for the spell affecting the somatic component for spellcasting, the spell doesn't say that it interferes, so I wouldn't assume it does, it is a high level spell after all. If your druid had the feat Natural Spell, this DM would be even more inclined to approve it.