To look after your sails do not let them flog. They should be stored dry, under well ventilated, conditions. Dry out the sail before leaving it on the boat. Avoid drying out the sail by hoisting it to flog in the breeze. When flaking the main ensure the foot is loosened. Avoid harsh creases when folding the sails.
Blood and mildew can be removed by brushing the stained area with a dry stiff brush, removing as much as possible. Soak only the stained area in a mild bleach solution of fresh water for 2 hours and scrub lightly. Rinse with plenty of fresh water.
Rust can be cleaned by using the commercial rust removers.
Oil and grease can be removed by dabbing the stained area with acetone and then rubbed with a clean rag. Once the stain is lightened, scrub the area with detergent and a fresh water solution. Rinse thoroughly.

For a brand new sail. If a good days sailing is in 15+ knots and the sailis are constantly being wet by spray, then a very light fresh water wash, allow the sail to dry and when packing away, roll the sail rather than fold. If on the other hand your sailing day is in light breezes with relatively no spray, then I would not wash the sail at all.

New sail fabric has certain qualities about it, that need to be retained for as long as possible. Constantly washing sails will eventually destroy these qualities and the sail will loose its stiff appearance.

As for rust and oil etc if they have been there for some time I would leave it alone. Applying any chemical in my opinion will only increase the rate of deterioration.

Cheers and happy sailing