I have had mixed results with those types of tools. This is both for the crossette tooling and the straight comet pumps. The tooling does not have a particularly fine finish. You might be able to polish things up with fine sandpaper or polishing paste. I'm not sure if brass tools work like bronze, but bronze tends to smooth itself with use. There are some other tooling suppliers www.woodysrocks.com and www.fire-smith.com that to me make much higher quality tools. They both sell only multi-use pumps, so you pay more, but also get more. Both owners are members here as well if you ever have any questions.
In terms of maintaining them, I'd suggest washing them off after use. Warm water and and old tooth brush always did the trick. Pay attention to the tip and the area where the cavity forming part meets the rammer. Also, be careful with the tools themselves. If you drop them they can bend and harm the tool. I would also avoid using any titanium. It can dig in and mar the metal easily. If you notice composition getting up between the sleeve and the rammer, I would stop and wipe things down with a damp cloth. Even without metal, things can get jammed. If you experience this and can't get them apart, soaking the whole thing in hot water often helps.
For color compositions, I would suggest a small press. An arbor press works wonders. I've rammed compositions before as well with okay results. I've always found the result to be a little less consistent.
Others who have used them may be able to better give advice on breaking the crossettes. Most of my tooling is from Wolter, who sadly passed away and is now out of business. The cavity from his tooling is significantly more narrow and thus requires different breaks. Granulated whistle would be a good spot to start. Metallic star compositions may not have the same issues, but flash compositions can give a distracting amount of light when they break.
For my preference, crossettes are best used in bunches. They make great shell inserts, but a mine with several is also quite nice. You can test your skill in getting them to break at the same time. The crossing of the various "arms" is to me the most attractive part. Because of this reason, tailed or glitter compositions are pretty popular. If firing them alone, treat them like a comet. A 1-1/8" or maybe slightly larger tube should be perfect for 1" comets. Be sure to measure them as well. It was not as advertised, but the similar comet pumps I had seemed to be metric sizes and thus slightly off of what you might expect.