Truk I've asked water babies about a beginners class for DD at around the same time as DS's toddler one, so we don't have to go more than once.
Re making up bottles. WHO state the absolute safest way is to make up fresh with water over 70°C. They still say that making up bottles with water over 70°C, rapidly cooling and storing in the back of the fridge is safe. Also back in 2012 when I had DS the formula tubs actually had instructions to make up fresh but had a note at the end of instruction saying where making fresh isn't possible next safest method was to make them with water over 70°C, rapidly cool and refridgerate.
tired do what makes you comfortable. If leaving lo would distress you don't - its not precious to want baby close, its natural.
Those with little ones suffering colds, I really recommend saline spray. Clears their little noses a treat.
DancesDD cluster feeds loads in the evening but is now fairly consistently going down at 9:30-10:30 and sleeping through until 6:30-7:30, every so often she has a quick 5mins each side at 3:30ish. DS was the same and once on formula at 9 weeks would do a solid 12-13hrs (he was a nightmare in the day though). When cluster feeding feels relentless I just tell myself at least it means I get more sleep.