I noticed today that my Facebook rescue groups had this link posted but I am not getting updates properly kn FB. Urgh. I could have been voting all along! Very welcome! Liked Stray Rescue on FB.
Keep trying.. or if you have a net, see if you can use that to coax him in the cup.. bring it up behind him as he gets into the cup to deter him from swimming out.
As for a heater - you could just run the heater part under hot water and use your hand to wipe away and scum on it.
I haven't heard back from the seller, but I should at least get the shipping back because Express mail was guaranteed to be here on 10/5 but didn't arrive until 10/6.