89 sedan deville oil pan gasket

i have a 1989 sedan deville with 157,000 miles on it. the previous owner must have treated it like crap because it has leaks all over the engine. i want to get the oil pan gasket replaced because its leaking alot and id like to know how much of a difficult job that is compared to replacing the transaxle fluid gasket. if its harder than i think it is i think ill just take it into a shop and have it done. i was also wondering if bosch platinum tip spark plugs are ok for this car (regular ones not duals or any thing). this thing is so much fun to drive i dont want to get rid of it.