The fuel filters should be replaced at every 30k miles. Try the many on-line auto parts sources, such as; www.autopartswarehouse.com or www.rockauto.com for the replacement parts. For example, they (RockAuto) list the primary fuel filter for $0.62 and the secondary filter for around $6.00 for your vehicle.

First, try the owners or maintenance manual with the vehicle. Next, try the on-line manual sources, such as; www.manualspace.com for the maintenance schedule.
Mercedes uses a Flexible Service System that takes into consideration your cars operating characteristics for service recommendations. They have gotten away from the 30, 60, 90,000 mile intervals. For the most part you'll just do lubrication services every 13,000 miles. For example, if you're coming up on a 39,000 mile service where they also recommend new fluid and filter in the transmission and new transfer case fluid.
I recommend doing an oil and filter change in between each lubrication service. At 2 year/26,000 mile intervals they recommend a new cabin air filter. Engine air filter is recommended every 52,000 miles, fuel filter at 65,000 miles and spark plugs at 78,000 miles. Brake fluid should be changed every 2 years.

How To Replace The Neutral Safety Switch On A 2003 Mercedes bens S430

First, try the owners or maintenance manual with the vehicle. Next, try the on-line manual sources, such as; www.manualspace.com for the maintenance schedule.
Mercedes uses a Flexible Service System that takes into consideration your cars operating characteristics for service recommendations. They have gotten away from the 30, 60, 90,000 mile intervals. For the most part you'll just do lubrication services every 13,000 miles. For example, if you're coming up on a 39,000 mile service where they also recommend new fluid and filter in the transmission and new transfer case fluid. I recommend doing an oil and filter change in between each lubrication service. At 2 year/26,000 mile intervals they recommend a new cabin air filter. Engine air filter is recommended every 52,000 miles, fuel filter at 65,000 miles and spark plugs at 78,000 miles. Brake fluid should be changed every 2 years.

Try this website for the remote starter information and comparisons; www.dmv.org/how-to-guides/remote.php

Several possibilities; low coolant level (refill with correct mixture of 50/50% water and anti-freeze), coolant level sensor is faulty (replace the sensor), or the vehicle was parked on an incline to cause the sensor to light.

Supplemental Restraint System, get it checked out by qualified mechanic.

These vehicles are known to have problems with seat control modules. You will need to replace both sides of the seat modules, this is the main thing that is draining your battery.