Here ADPro - more or less - works as expectetd. Yes, you have to adjust the MAXMEM tooltype. Nowadays pictures are much larger then they used to be at ADPro heydays...
And, yes, ADPro doesn't like to long file names.
Nevertheless I do not experience your problems - AmigaAMP just happlily plays while ADpro loads or does it's JPEG decoding or whatever.