I might be missinterpreting, but I'll toss it out any way. You can deliver a touch attack WITHOUT making a normal attack with a claw. The claw does no damage, but delivers the charge. Or you can go for the harder hit roll and get both. A distinct advantage to using natural attacks.
As far as holding a charge, if YOU touch anything, it dissipates. There are no restictions to having things touch you, otherwise the AoO you take from casting the spell would cause it to fizzle. Simply put, you do not have to be naked to cast touch spells.
For a creature like a tiger that has to have four on the floor to move well, I would rule that you have to go half speed, or no more than a 5' step, befor delivering the attack. Otherwise you would have to touch the ground and dischage the spell. For rough terrain or slick conditions, I'd add a Balance check, or +5 to the existing check. The above paragraph is opinion only.