Glad you had some fun with that.
About explosion range - still tweaking it, thanks for reporting.
About exploit with sticky and frozen block - yes, this is intended. Happy to see you discovering it!
We call it `bethesda jump` (similar to glitch where you can jump of items dropped from inventory which exists in Bethesda games from oblivion times, i believe). The thing with it is that if player does not know about it - it's fine, levels are completable without it. If they do, however - it's just easier.