High ISO does not really matter, as you don't really want to go higher than 800 or so. Not to mention mid range DSLRs usually have decently high ISO.
Splash proof - most of the DSLRs can handle a little bit of rain drop, however, there is aftermarket plastic case or ziplock bag for those who need extra care.
I would look for : steady tripod, lens and lens filter. Lens filter is really important, you can buy a $1000 lens and get a quality of $200 one because of bad lens filter.
For general purpose, I would say Nikon D5300 or D5500. Look around couple of places and you'll be able to find cheap ones.