You don't have to use the yarn called for in a pattern. People subsitute yarns of their choice all the time. There are some considerations when substituting. You need to find a yarn that will get the gauge you need and have a similar quailty to what was called for if you want the same look as the item shown. Like Sue said wool blends can be machine washed and dried. I did have a sweater I knit for my granddaughter ruined by machine drying it when it was okay to machine wash it. Should have laid it flat to dry (it was washable wool). There are also cotton blends that can be machine done.
I have to say this, although I have not tried it.... I had a yarn shop ower tell me she machine washes all her wool and my own daughter tells me she machine washes hers, even expensive cashmere sweaters and has never had any ruined. You need to use a low agitation and short cycle and warm or cool water that doesn't change temperatures for the rinses. You can also put the item in a lingerie bag to minimize surface contact.
Often a garment, when you make it, is blocked before it is pieced together. You can do a careful measuring and all that if you want. I usually don't do a super job with all that, but just laying an item out and spraying it, or wetting it and laying it out with some pinning or not will help an item to look more professional. Sometimes I just wash it or wet it and roll it in a towel to dry it a bit and then lay it out so that it looks about right (ArtLady, don't listen in :-)), and sometimes I don't do anymore than that or I have been known to put table knives along the edges to hold down the edges.
After an item is made and it use, I've never really blocked (as in measuring and all that) it again. I wouldn't say it may not be needed with some yarns but with the wool I have used, just laying it out to the shape you want and leaving it to dry is all I have done (I'm thinking of sweaters). It's not that hard, and only what you do with a lot of items you buy that say "lay flat to dry".