It actually needs a slight amount of up-elevator to stop it speeding up in the slip.
I don't know whether that's universal, but it's true of every aeroplane I've slipped. You do need a bit of back stick to prevent the speed building up in the slip. Not much point arriving accurately at the threshold by slipping, only to float half the length of the strip through excess speed!
As regards the lack of AoA indicators in aeroplanes, it's always struck me as a major omission. Fast jets, Concorde, and gliders (the ubiquitous 'wool tuft') have them. Not many other aeroplanes I'm aware of do.
There are several instruments in the aerobatic aeroplanes I've flown I'd gladly trade for one.