Resists...the Paladin is supposed to be the best tank/defending class....he should be tough to hurt. Both physically and magically. Even then, I'd say a caster can match him if he devotes spells to it. Whether by casting the Spell Resistance spell, using Mirror Image or invisibility to outright not be targetable by enemy mages, casting emergency force sphere to instantly (as an immediate action) deny line of effect, and so forth.
Not a problem.
Action economy: Is this a joke? Many classes are better or equal action economy to the paladin's attack + self-heal schtick. Summoners have pets as strong as fighters plus full casting at the same time. Bards can eventually swift perform and cast spells. Magus can cast a spell and full attack. Any primary caster at higher levels can use quickened spells, and at level 15, can quicken for free (Spell Perfection).
Absolutely not a problem!
Smite: Ok, this one, I agree Paladin is VERY good at his job. Solo evil bosses are just speed bumps to a Paladin, and that definitely can make it tough to make challenging fights for the DM. But on the other hand, I've found Paladin is pathetically, incomprehensibly terrible vs. groups of evil foes. Even when he gets Aura of Justice, that's to let the whole party wail on one guy, not to let the paladin wail on the whole evil enemy party. Their offensive spells are likewise pretty much all single target. The best thing a Paladin can do vs. your bog standard horde of undead is to use Channel Energy....which costs him twice as much to use as it does the cleric and bites right into those swift heals you hate so much...and does pretty crummy damage (especially when it's will for half; undead are great at will saves).
Slight problem; requires some adjusting your encounter plans. I do not think Paladin actually being awesome against the things he's supposed to be awesome against is so bad, though.