I have just done your letter with the treatment so that is ready to go next time someone comes, probably sunday though!
The photo you sent me of the female shrimp, she has eggs in her saddle (I zoomed in) and looks very healthy so hopefully she will help you restock! Early days yet with her though!
Your tank hasn't been going long enough to get an infestation of hydra so that shouldn't really be an issue beyong next week when you treat it!
Try to get photos of under 1mb as I 'beelieve' that to be the file size limit? Try one first as you can then add the others by editing the post.
All shrimp go pink in the flesh when they die (like cooked prawns) so sometimes that can be misleading, ie that one you thought had a bacterial infection, may not!. Similar with the eggs, they are usually yellow but through the blue shell will probably look greenish, when they develope they usually go grey as the yolk in each is used up! I'm not sure if there is any obvious signs when a shrimp dies from ammonia poisoning/affects, I suspect not, maybe JayC knows?
Even if you are now on top of everything and the tank looks settled, as JayC pointed out, the shrimp could be sick or weakened so they may still die occasionally, fingers crossed though that that won't happen after all the hard work you are putting in. Shrimps need stable conditions though so don't go too mad with changing/trying different things etc as that may make things worse!
Simon