Check out Tom Rosenbauer's book on Prospecting for Trout, it'll teach you more about reading water.
And now on to your new questions:
-First of all, note sun position when determining your placement so you aren't silhouetting yourself/casting shadows onto where the fish will be. Trout will typically be where the feeding is best, but they won't want to be in spots with direct sunlight too often because this makes it easier for predators to spot them (particularly if the water is shallow).
-Yes, you should most often be looking for places with slower water speed HOWEVER when I say this I mean the specific places the trout are. The trout can be in the riffles but the individual lies for each trout in said riffles will be areas with slightly slower water speed to allow the trout to be comfortable while feeding (which is why it makes more sense for a fish to be sitting in front of a rock, where there is enough disturbance to slow the water down but allows the fish to see all approaching food, rather than behind a rock, though that doesnt meant there won't also be trout behind the rock...). The trout will also need good access to a hide in the event of predators, or you.
-Dry flies are best when you see fish rising. If you don't, then go with nymphs or streamers. Certainly you can try dries when fish AREN'T rising and maybe you'll get lucky and attract interest. But there is a reason that nymph fishermen tend to have the best catch rates... However, dries are super fun to use so if there is a hatch going on, try to match it and good luck. If they are rising but you can't see them eating bugs off the surface, they're probably eating emergers. Try an emerger pattern for the same species of bug you see on the surface, or just a general emerger you have confidence in.
-I don't really change my strategy except I know that I can be a little more liberal with regard to my own body placement when accounting for throwing shadows across the water. However, if there are distinctly shaded spots vs. less shaded spots, the fish will likely favor the shaded lies.
-Depending on who you ask, it is ALWAYS a good time for a streamer. You can dead-drift them, strip them, swing them, run them under an indicator, etc. There's a reason the woolly bugger, a streamer, is so popular! However, high, dirty water is particularly good for streamer fishing, such as after rain storms. During rain storms is also a good time, as usually wary fish tend to drop their guard a bit, and big fish tend to want bigger meals (though this is not always the case... I love when tiny midge patterns work
). "Swinging a streamer" is just a method of presentation where you cast across stream and mend so as to have a tight line, allowing the fly to "swing" through the water at the end of the tight line. This keeps you in connection with the fly and you should feel even the lightest of taps. This can be a great way to fish once you gain confidence in it (I'm still working on it...) but you can swing any fly. In fact, if fish are hitting emergers, a swung pheasant tail, hares-ear or prince nymph may be just the ticket and this makes for some pretty awesome takes!
For the record, this could be all wrong, but I hope some portion of this helps...
I left this part out, but am now curious... what kind of knots are you using? As an Eagle Scout I love knots, and as someone who has fished for tarpon and has family members on the board for a tarpon tournament in my home town, knots become larger than life issues
I have recently learned the non-slip mono loop, which is a great knot for fishing streamers, it really imparts some extra motion in them and though I haven't had much of an opportunity to actually present it to fish yet, it looks GREAT in the water. It's also surprisingly strong (which I learned when I caught a nice solid branch-fish). Otherwise, I use the improved clinch for most tippet-to-fly knots. However, I've recently learned that the double improved clinch is on average one of the strongest knots, but the difficulty of tying it with many of the smaller flies I use keeps me happy with my usual improved clinch. I did a brief tour with the Davy knot but I would not suggest it. Speed does not make up for the number of fish you lose when the knot decides to fail, especially when using lighter tippet... I'm also a big blood-knot fan because of the combination of strength and slimness. I always like hearing what knots other fishermen use, however!