Which of the anti-epileptic drugs affect the metabolism of the Pill (oral contraceptive) and what are the implications of this? Which drugs are safe to use in combination with the Pill? 

Anti-epileptic drugs that affect metabolism of the Pill

Phenobarbitone, Carbamazepine, Phenytoin, Oxcarbazepine, topiramate. These drugs decrease the effectiveness of the pill, and could as a result lead to an unwanted pregnancy

Pills that do not interfere with the metabolism of the pill.

Valproate, Lamotrigine, Gabapentin, Levetiracetam. Oral contraception does however decrease the plasma levels of Valproate and Lamotrigine 

Can oral contraceptives also affect the effectivity of the anti-epileptic drugs?

No

How does age affect the kinetics of these drugs (from neonates to old age)?

Babies and children metabolise Epileptic drugs faster than adults.

Neonates metabolise slower. 

Elderly will need a lower dose because liver and kidney doesn't function optimally.

In which cases is plasma blood level monitoring indicated?

Phenytoin, because Phenytoin starts off with 1^st order kinetics and then zero order kinetics once the plasma concentration of phenytoin is > 10 ug/ml. The drug can then accumulate and then reach a toxicity level which is very dangerous. Its also important when enzyme inducers are used. Lamotrigine can be used with Carbamazepine. Carbamazepine induce liver enzymes and the enzymes can break lamotrigine down.