Silentknyght: Your recipes look sound, so I'll comment on procedure:
1) Most municipalities use chloramines in their water, not chlorine. Boiling for 5-10 minutes won't get rid of chloramines. The simplest way to deal with them is to add campden tablets (metabisulfate) - approximately 1/4 to 1/8 tablet per 5 gallons. Alternately, you can use filtered water (counter top carbon filters are fairly inexpensive) or buy reverse osmosis or distilled water.
When making extract beers, if you want to taste the true nature of the malt extract, you need to use distilled water. This is because LME is nothing more than extremely concentrated wort, while DME is dried wort. That means that all the minerals from the mash and sparging water are concentrated in the extract. Adding your own water, with its own minerals, adds an extra dose. For most purposes, this doesn't really matter, but if you live someplace with really hard water it might make a big difference, even if you attempt to precipitate your carbonates.
2) Keep your water temperature below about 168 degrees F when steeping. Higher temps can extract tannins (astringent - like sucking a tea bag) from the grain husks.
4a) No big deal. Slight concentration and darkening of your wort. For a wheat beer, only matters if you're really concerned about competition.
4b) 45 minute boil on bittering hops is a bit short, but it's a hefeweizen so you don't care about maximum hop utilization.
4c) Closed boil for extract really is only a problem if you're worried about boilovers. The idea behind an open boil is to drive off DMS and other sulfur compounds found in some varieties of malt. A full rolling boil helps with hop extraction and hot break formation. Speaking of which, Irish moss added 15 minutes before the end of the boil will help with cold break formation. Also, for the IPA, for full hop utilization, you might want to increase your boil time after you've added your bittering hops. 60-90 minutes is more typical, 120+ minutes is not unheard of.
6) Spend the $30-40 for a coil of soft copper tube, a couple of compression fittings and some food-grade plastic hose and make yourself a simple immersion chiller. If you can bend copper tube around a corny keg or something like it, you can make an immersion chiller in about 30 minutes. Unless you sanitized the hell out of your sink, it's probably the dirtiest place in the house. (I'm not picking on you in particular, it's one of those ugly food safety facts.) An immersion chiller will minimize risk of infection, give you a better cold break, get your wort down to proper pitching temperatures and shorten your brew day.
7) Your water was sterile, right? If it was standing around overnight, that's another source of potential infection. If you stored it in the refrigerator, unless your refrigerator was sanitized, then the water container, and the water if the container was open - is covered in microcritters. (Another sad food safety tip.) Racking (using a siphon starter, not your mouth) is a slightly better way to get your beer off the cold break and hop sludge. Just rig up something so the hop sludge doesn't clog your siphon. A copper wool scrubbing pad wrapped around the end of your siphon works adequately.
8 ) Dry yeast might need a starter, depending on age and cell count. Making a yeast starter is another one of those simple things you can do to improve your beer.
9 A&B) 74 degrees is way high for the yeasts you were using. Your yeasts were probably producing all sorts of off flavors. In particular, your hefeweizen yeast is probably throwing massive amounts of banana esters, clove phenols and higher alcohols. Get your temperature down to 66-68 degrees or brew styles which can stand the higher fermentation temps. (i.e., some Belgian styles). Also, remember that yeast makes its own heat as it metabolizes sugars. That means that your raw beer was probably a bit higher in temperature.
You didn't mention a terminal/final gravity reading (F.G.) for your beer at bottling. Wild temperature swings might shock the yeast into dormancy, possibly resulting in "stuck" or incomplete fermentation. Not so likely this time of year, unless you're someplace where it gets hot during the day and very cold at night.
10-12) No problems. Hefeweizens traditionally have a lot of carbonation behind them, so you might have increased the priming sugar slightly for that batch.
A turkey fryer is bog-standard equipment. Its only disadvantage is that there is a lot of heat under your brew kettle. You can get scorching or caramelization of the wort and boilovers can be fast and nasty. If you have a problem with scorching, you can rig up some sort of flame tamer to go under your pot. Boilovers can be handled by an open boil or by having a squirt bottle full of dechlorinated water you can spray to knock down the foam on top of your kettle. Caramelization really isn't a problem for the styles your brewing, especially since you're using extract.
To differentiate the two styles, try a longer boil time for the IPA and bigger flavor and aroma hop additions, plus dry hopping. For the hefe, possibly a "mini-mash" (like steeping, but hold the grains at ~155 degrees F for about 45-60 minutes) using some wheat malt and maybe a bit of caramel malt.
Without knowing what flavors you're detecting, I'm guessing.
Water derived: Chlorophenols (medicinal, band-aid, mouthwash), excessive mineral harshness ("powdery" or chalky), harsh hop character.
Infection: Just about anything: sour, sulfury, smoky, buttery, vegetal, etc.
Yeast problems: "green apple" (acetaldehyde), buttery (diacetyl), phenolic (peppery, spicy, smoky, medicinal), solventy (higher alcohols), estery (fruity, floral). Excess sweetness.
Ingredient derived: "cidery" notes due to poor-quality or old malt extract, grassy, metallic.
Process derived: medicinal notes from residual sanitizer, metallic notes from copper or iron in contact with raw beer.
Take a look at the flavor faults on the scoresheet here: http://www.bjcp.org/docs/SCP_BeerScoreSheet.pdf
If you can describe the flavors you're tasting in more detail, it would be easier to figure out what's going on.