Hi 'sprinter'
To answer your questions.....
1. For removing excess oil spray along door sills, bottom of the doors, door hinges/jambs, etc, I would recommend some Orange Lightning (made by Spray Nine). If you spray a bit onto the surface, wait a few minutes and hit it with the pressure washer it should remove 99% of it with little or no residue leftover afterwards. If you do not have a pressure washer handy, spraying some of the product onto the surface and wiping with a cloth will also suffice, but will take MUCH longer. As a side note, if you're using a cloth to remove excess, use ones that are cheap or old that you can throw away afterwards. In all honesty, they won't be worth keeping and the last thing you would want to do is try and throw them into the washing machine at home and have all that residue stick around for the next load of WHITE clothes

2. For removing the salt stains from the carpet there is only one tried and true method that I use. I generally take my garden hose and shop vac and go at it until the salt is completely gone. Now before people get worried, its not as bad as it sounds and as long as you are careful its fine. First you have to turn the tap on so that you have a nice little trickle of water coming out of the nozzle (NO FULL BLAST) and get the wet-dry vac ready. For the Wet/Dry vac, it should be on the powerful side of things as to remove as much excess water/moisture as possible. Turn the vacuum on and have it ready on one hand, with the garden hose/nozzle in the other, and start soaking the salty areas of the carpet following with the vacuum IMMEDIATELY to remove all of the excess water. Please note, you should not FLOOD the carpet so that a nice pool of water has time to form on the floor board (this is a no-no). You only want to use as much as you need to get the job done, so don't go-to-town. In addition, this method also works for ground-in dirt and heavily soiled areas as it flushes everything out of the carpet which is then removed immediately with vacuum. Afterwards, be sure to clean the area with a carpet cleaner or carpet-safe all-purpose cleaner and brush, following with a thorough vacuuming afterwards to remove as much excess water/cleaning product as possible.
For carpeted floor mats, the process is much simpler. Start by vacuuming the mats off to remove the larger debris. To clean carpeted mats properly you NEED a pressure washer. The reason I say this is simply because it is the only way to ensure all of the excess dirt and more importantly soap is removed from the carpet. If there is excess soap left in the carpets, once dry they will attract dirt quickly and become dirty again in no time. Start off by pressure washing the mats to ensure they are SOAKED. Please note that you should keep the pressure washer nozzle a SAFE distance away from the mat to avoid damaging the carpet pile. Depending on the PSI rating of the pressure washer, 3-5 inches should be enough (remember you need to remove all excess cleaner and dirt so use a distance that works for you and accomplishes this without causing damage). Next spray the mat down with cleaning product and brush with a carpet brush to work in the cleaner and help aggitate/remove the dirt. The next step involves using the pressure washer to remove all excess cleaner and dirt. Keep rinsing the mat until there is no more murky or brown water/dirt coming off the mat, and once dry grab the trusty wet/dry vac and remove the excess water and moisture. On a clear, warm, sunny day, leaving the mats out all day should be more than enough to dry them up -make sure they are dry before they are re-installed in the vehicle as to avoid any damp and musky odours. The same also goes for the interior in that you should lower the windows or open the doors to allow the interior to fully dry.
As a final step, grab some of your favourite spray air freshener (my personal favourite, and the one I use in all clients' vehicles is "Vanilla", made by a company called "Big Fresh", which can be found at any local CT or Wal-Mart. Meguiar's makes a product called odor eliminator which is also a good choice too, however it is best used in situations where there is a need to remove offensive odors.
Good Luck and if you need any more advice or have any more questions, please don't hesitate to ask!
Cheers!