Spy Glass really helps for the flights. If you have a Weathervane then you might consider activating both and without instant returns you'll be able to do lots of TP (39 min) and Jet (< 2 hrs) flights.
For Leprechauns I don't know whether any bonus would help. Perhaps a Sky Captain?!
I'll consider activating some bonus in a day or two. At this moment I'm missing only 2 small harps to finish the second challenge, and just one pipe to finish the first one. Perhaps they drop meanwhile...