Getting anything done to your apartment in NYC requires endless patience and the willingness to make endless phone calls. Over the course of the seven months I've had to locate a plumber, an electrician, a blinds installer, a window washer, a wallpaper installer, and a "man with a van" mover; with the exception of the mover (thanks CitiMove!) locating each one was an incredible hassle.
That being said, unless you have described the job wrong, the earlier commenters are right: You need a carpenter and a plumber, unless you're relocating walls and doing major plumbing work to put in a W/D from scratch.
If you're just having a W/D installed into an existing hookup and can't get it from the store you bought from, I got adequate service from Drain Brain in Brooklyn - although I had to read the manual with the guy, at least they returned phone calls and they were significantly cheaper than some other places I called. I think I paid around $100, and got quotes of up to $300 or more. When calling, make sure you can visually describe your hookup and know the model of your machine in case asked.
For shelves, if you want something fairly simple Gothic Cabinetcraft will build things to order and in some cases may be willing to install onsite. You can also take the classic NY approach and just ask your super if he would be willing to do the installation for a fee or can recommend someone who will; bear in mind that you often do get what you pay for, and people will often claim they can do certain jobs they don't know what to do.
And even if you don't feel like it, be unfailingly courteous and polite to every single workman you deal with. If someone feels you're not going to be a hassle to work for they might be more willing to do a smaller job - and will certainly do a better job. And don't expect to get good work out of someone after bitterly arguing about their fee first - it's better to comparison shop first so you know what is a reasonable price to pay, then ask for a reasonable discount from someone who's in the ballpark.