I always wash my engine at the do-it-yourself washes. I usually take about twenty minutes to get to the engine, if not longer, so I figure by that time the manifolds will have cooled off enough to where the water (already warm-hot at the wash I use) won't hurt them. This reminds me.... I haven't taken any engine bay pics of my car lately....

I've never had any problems washing my engine with anything, including car-wash pressure.

Don't use a commercial pressure-washer. It produces enough pressure to damage plastcis and wire insulation. Keep the wand at a distance.

Using a degreaser and a low-pressure garden hose sprayer is preferred.

I only used a pressure washer on mine once, when I first bought it, the engine was nasty, but I used two cans of citrus degreaser, that loosens up all the crud so you dont have told pressure on anyone spot for a large ammount of time, generally I use low pressure now.
Never had an issue

My engine'* filthy, never been washed in its LIFE. What stuff do I have to cover up? I know I have to take out the battery...

You don't have to take out the battery, unless you're trying to clean the area under it and it'* in the way. You don't really have to cover anything, unless you have an open cone filter in which case you should cover that. You can cover the alternator if you want, or just be careful not to spray water or engine degreasers/detailers inside it.

Don't hit the coil packs, or some things like LIM coolant sensor wiring, etc...

I try not to spray the injectors dead on either, or the trans wires/plug.

Eee... I need to learn these parts :(

Since Im away at school and dont have access to a hose. I usually go to the coin operated car wash and degrease everything really good with a brush and spray. And then i take some simple green and scrub some more. Then spray clean carefully....

I have to get some of that simple green stuff, a lot of people I know talk about how good it is.