1. I'm using Super-Prodol in powder form (mix with 1l water @20?, stir, etc.) When I'm done with the dev stage, do I pour it back into the jug or toss it out? The package isn't really clear ...
As others have said, developer
can be re-used, but most home darkroom users don't do it. Many developers can be used at a variety of dilutions (undiluted, 1+1, 1+3, etc.), and for economy or to subtly vary the results, people will use it at the higher dilutions. Don't dilute beyond what the manufacturer recommends, though, since that can cause problems.
2. On the handy-dandy dev time chart on the back, it gives different times according to dev temperature: 18?, 20?, etc. What difference does it make what temp the dev is at?
Others have answered this, but I'll add that most chemical reactions, not just photochemical reactions, proceed more quickly as the temperature is raised. Also, if you move on to developing your own color film, temperature control will become very important. C-41 films are meant to be processed at 100F, and deviating from that, even when you also adjust the times, can result in color shifts. With B&W, though, you can vary the temperature within a fairly wide range and you'll be fine, so long as you adjust the time accordingly.
4. If I use Fuji developer, do I have to use Fuji fixer? Can I mix and match?
Others have correctly said that you can mix-and-match brands of chemicals. There is, however, one advantage to sticking to one manufacturer: If something goes wrong and you call the tech support line for help, the manufacturer can't point the finger at another manufacturer! This is probably most important when you're starting out, though, so if you've got a stock of Fuji products I'd just go through them and then when you need more of something, buy whatever's convenient or appealing.
2. Developer you can reuse if you want, but nothing else, right? It is my educated guess that stop, fix & quickwash would be contaminated (especially stop) if you poured them back into their containers after use, right?
In most cases, fixer and indicator stop bath are the most re-usable chemicals, at least in a home darkroom. I wouldn't re-use vinegar used as stop bath, though. Check your fixer's instructions for how many rolls it can handle, and don't use it for more than that. Also, be sure to dispose of your fixer properly, which means according to local laws, which vary substantially from place to place.
3. I'm using 1l bottles bought at a $1 shop to store my "potions". I've found that in doing 120 chemicals get used up rather quickly. What kind of containers are people here using? And is it safe to use the kitchen sink as long as I wash everything afterwards?
People have differing preferences with respect to bottles. Personally, I prefer glass because it's impermeable to air, which helps with storage life. (At least theoretically and according to what I've read; I've never done any controlled experiments myself.) I re-use glass bottles that used to store food (spaghetti sauce, root beer, iced tea, etc.), supplemented with some Boston rounds I bought online for smaller quantities. Other people prefer plastic because it doesn't break. If children live with you, you might want to avoid re-using food bottles because the kids might mistake the photochemicals for food, particularly if you store your photochemicals in the kitchen. As to using the kitchen, plenty of people do this. I do advise care in cleaning up, and I probably wouldn't put food directly on any counter that might have had photochemicals on it, just to be on the safe side.
Oh, and back to bottles: Try to keep them as full as possible, particularly for the developer; exposure to air causes the developer to deteriorate. Different people have different approaches to this problem. Some drop marbles into partially-filled bottles to displace the air; others use bottles of varying sizes, keeping most completely full; others use an inert gas to "blanket" the chemicals in a partially-full bottle; and still others use vacuum pumps to reduce the air pressure in partially-full bottles.
5. Should I be using gloves? I ran out a few days ago and I'm getting sick of dev smell and worried about health risks.
For B&W, I don't use gloves, although I probably would if I used pyro developers. Most B&W chemicals just aren't that dangerous. OTOH, metol (or possibly contaminants that are commonly associated with metol) has been known to cause contact dermatitis, and the reaction can grow in severity with prolonged or repeated exposure. Thus, if you use a developer that contains metol (most do, including D-76), you might want to consider wearing gloves, particularly if you have known allergies or sensitive skin. Some developers, such as Kodak's XTOL, are metol-free, and so don't pose this specific risk.
I'd like to get my hands on some Rodinal (heard it's not a fine-grain developer) but I don't know who'd stock it over here
If you can't find Rodinal locally, you could try mixing it yourself. Several formulas are available online and in books. Unfortunately, most require you to obtain a chemical called para-aminophenol or a minor variant of it, and this is likely to be hard to find. One easier-to-mix alternative is called
paRodinal. This is mixed using acetaminophen (Tylenol), sodium sulfite, and sodium hydroxide (lye), all of which are relatively easy to locate. Once in solution, the sodium hydroxide converts the acetaminophen into para-aminophenol, and the resulting brew is very similar to "real" Rodinal. OTOH, there's always the risk that your acetaminophen will have some biologically inert substance that'll cause problems in a developer, so if you try this, you should definitely develop an unimportant roll before you develop anything important with it.