RE: Speed reducing maneuvers
pop up/wall would work if you have the power to pull out if your down low. to do this chop power a split second before you pull full up ele , as the nose pitches up relax the ele a bit to just bring the nose vertical and add a little power at the same time. you can transition out with full power if you have the motor, if not just power up and nose it over a bit. I do it all the time with my funfly's, usually transition into hover or roll's/snap's on the upline...never used it to slow down though I have flaps for that. I assume you only have one ail servo so flaps/flapperons are not an option, other than a wall/pop-up and what your curently doing I can't think of any air break type maneuvers. best thing to do is fly a plane more suited to the enviorment(slower more agile) or fly some where with less obstructions.
John