Perhaps somebody hanging here has some practical experience with these matters?
In the US, where I'm from, it is not permissible in the workplace, as I recall, to put an employee in one of those half-mask respirators until they have been screened by a doctor. There apparently can be some problems in one's ability to breath in against the slight resistance, etc. Also, the user is not permitted to have facial hair in the sealing area of the mask as this can affect the seal. Finally, the user must be trained in the proper use, including cleaning and sanitation after use, as well as have a "fit test" performed. The fit test uses some sort of material that the user can smell or taste if it leaks through the mask; in our operation we used a material with the odor of bananas. Because of these issues, it was far preferable to deal with things by so-called "engineering controls," aka ventilation. Of course the ventilation must also be tested routinely to make sure that it is protecting the employee.
It may sounds like I'm going a bit overboard on this, but hey!, you started it, right? (wink). You might note that I referred to "the workplace;" in the US this means a company with more than something like six employees, and these are essentially government regulations to protect employees from potentially bad behavior by the employer. Individuals outside of work are pretty much free to do as they wish.
See.
https://en.m.wikipedia.org/wiki/Respirator_fit_test
Regarding what sort of mask you should use, you should look at the individual MSDS (material safety data sheets) for each chemical you use; these make recommendations for "personal safety." As a general rule, I'd say that mixing low pH fixers might suggest an "acid gas" cartridge, for a high pH fixer an ammonia cartridge, and for many other things in general, an organic cartridge. It sounds like the cartridges you are looking at is a "do-all" sort - essentially all of the above stacked together.
There can also be also be fine particulate (dust) if mixing from powders, in which case a particulate pre-filter may snap on over the cartridges. You should keep in mind that if you really need protection from these powders, they are probably also settling on surfaces in your mixing area, and may cause problems later when stirred up.
I'm speaking from real world experience in a large photofinishing operation, and these are things that we actually did, mainly in our chemical mixing operation. But we were mixing several thousand gallons of replenishers daily so things have to be done carefully.
You should also be careful about handling the chemicals during normal use. The color developers are considered to be skin sensitizers; after repeated contact certain people may develop an allergic reaction not unlike that of poison ivy. Over the course of a lot of years I've known of perhaps three people who did so; they were no longer able to work with color developers. It was pretty much their own fault fwiw, they were processor operators cheating on the rules by not bothering to wear gloves, or whatever, cuz it didn't seem like a big deal to them. As for myself, as a rookie QC tech I had spent a lot of time up past my elbows in color developers (always washing up with phisoderm (?) the recommended low-pH hand cleaner of the day). But when my boss suddenly developed a severe case of contact dermatitis I (mostly) quit handling with bare hands. (The boss was never able to handle the color developer again, without gloves; if he even touched a doorknob that once had color developer on it, his hands would break out.)
I've never done color at home, but if I did I'd probably just wear disposable nitrile rubber gloves and a smock of some sort when handling the chemicals. And make sure there is some sort of general exhaust fan. If the smell was bothersome to me, I'd probably see it as just not enough exhaust rather than go for a respirator. But in your case, as your say you already have some sort of problem, you may need to do more, I dunno.
As a note, to evaluate an exhaust system design, we'd use what they call "smoke tubes," something that puts out small puffs of "smoke;" you use these to see how effectively air is pulled toward the exhaust (you may have "dead spots" or whatever, in your room). If you smoke, this makes a convenient way to check the air flow. Or even just light a match and blow it out, but it only lasts for a few seconds.
