Is the super-glue permanent enough? I'm worried that you'll one day have a family of dicky-birds sent crashing to the ground.
Different birds like different sized entrance holes, and the hole size depends on the species you hope to attract.
As a rule-of-thumb, I usually follow this guide...
25 mm for blue, coal and marsh tits
28 mm for great tits, tree sparrows and pied flycatchers
32 mm for house sparrows and nuthatches
45 mm for starlings
3 ft for vultures
A small box with 100 mm high open front may attract robins or pied wagtails.
A wren would need a 140 mm high front panel, while spotted flycatchers prefer a low 60 mm front to the box.