distilled water is what I recommend, NOT tap. But even with distilled you really need to test the water before making the silver bath in its entirety. Take nothing for granted, take it slowly and you should be fine. Have you taken a workshop or done WP before? if not, ask questions and dont be afraid to search on the forums, very likely someone has had a similar problem and asked the question.
Also, some will report that a full alcohol salted collodion is considered more tender than one with ether/alcohol mix others will disagree and say its tough as nails. Approach the salted full alcohol collodion as if it will tear if you look at it the wrong way and it should stay on the plate. I havent worked with a full alcohol version yet but want to try it out, just to see if it is visually different.
DONT be tempted to try lots of formulas for developer, collodion or true negatives. Get the ambrotype version down, learn the process know how your lens/collodion sees the light, generally get very comfortable with the whole deal. after that, play around. Having done lots of playing, there are differences in teh collodion formulas but hard to see the differences. This means you really have to know the equipment/process to see the diff. Fixers on the other hand, worlds of differences depending on concentrations, hypo vs kcn vs rapid fix. The type of fix is an easy difference to see. Me personally, I use what ever fix I need for the image at hand. I am not a KCN evangelist. I am an amateur wood worker and equate things to tools. If you know your tools well, some better than others, you tend to gravitate to known tools. However, when you know your tools really well, you know which tool is best for the job. That is my philosophy towards most things that I do.
Build the experience, be safe, follow MSDS best practices and have fun.
Erick