Sorry to say this James but you're seriously overstocked there for a 60 litre tank with a tiny filter, and especially so as the tank has only just cycled.
Monitor your ammonia, nitrite and nitrate daily and be alert for any reading above 0 on the first two or above 40 on the third and do a 25% water change whenever it happens.
The Balloon Molly and Koi Angel will be too big for your tank - the minimum tank size for an Angel is 140 litres. The Molly, being the Balloon type will be sensitive to poor wate quality. I suggest you return those two asap, but even then you'll still be overstocked.
With regards to the stingray 15, I helped a friend of mine buy a second hand 60L tank from an LFS recently which came with this filter and was advised by the shopkeeper that the stingray had problems with smaller fish getting stuck in it and he specifically didn?t recommend it for neons which as chance would have it was what my friend was looking to keep. I?ve always found this shopkeeper trustworthy and since the tank itself was a bit of a bargain my friend bought a new eheim filter.
Ok, the plan is to return the Molly and Angel, and since the filter doesnt seem to be suitable for the tetra I think I should return them as well for their own safety. And I'll also get another couple of cories.
Lesson here is do my own research instead of trusting a bloody salesman, Im rather peeved off with the whole situation to be honest.