mylesd: No problem w/ throwing the poncho liner into the washer. If you're worried about it, just put it on gentle cycle. Any detergent will do. You can drip dry or toss in the dryer (low heat or tumble dry). I'd wring it out before placing in the dryer. Poncho liners are pretty bombproof but don't like hi-heat dryer settings.
Sleeping bag is problematic. Is it an older OD green cloth mummy containing feathers? Is it a newer cloth green bag w/ synthetic fill or the even newer ECWS (Wiggy's Modular System) black nylon outer bag/sage green nylon inner patrol bag (both w/ synthetic fill)?
If filled with feathers/down...I suggest taking to dry cleaning (just like a wool suit) and then hanging the bag (unzipped and spread) for a few days to allow remnant dry cleaning fluid to completely evaporate from the inner fill. Otherwise, handwash with down bag detergent (available from backpacking stores or REI) or mild detergent like Woolite. If your washer has a DELICATE cycle, you can use the same detergents. Don't put a down/feather bag in a dryer! Just gently wring it and hang to air dry for several days. You will probably only need to do this once or twice during the lifetime of the bag unless it becomes severely soiled. I still have (and use) a Camp 7 down bag I bought in 1984 and have only handwashed it twice.
If synthetic fill bag: Same washing instructions as for down bag. Then wring and let partially drip dry. Then tumble dry on gentle cycle. Then hang for open air dry for a day or two or three.
Bags usually have batts of fill sewn into cells or baffled compartments with nylon thread. Once a bag becomes wet the fill (down or synthetic) becomes heavy and will bunch up or become compacted at ends of cells or baffles. Additionally, the cells fill with water faster than they can drain. Energetic motion by washers or dryers will cause seams to rip, baffles to tear, and fill to be strewn from one end of bag to the other (if not outright ejected from the bag!).
A surplus military bag is a tough animal as sleeping bags go. Just wash and dry it gently taking care to gently but firmly wring excess water before drying. After the bag is dry, hand fluff it to evenly distribute fill material and re-inject air into the fill. If possible, store the bag loose (not in a compression sack). I hang mine in the closet from the toe of the bag or just suspend it in a hammock hooked to two nails in the wall. Or just stuff it into a large clear plastic zip bag like most bedding sets are sold with.
Enjoy your bag...
Thanks