Yes, IMO. By AWT they've a foamy structure, the density of which increases toward center. The foamy structure of dark matter is such structure, as observed from inside.
2) Do black holes retain any memory (mass/energy/charge/spin/particle type) of the matter they swallow?
Yes, or they couldn't cummulate matter at all. AWT considers black holes as a dense neutrino/quark stars
3) Do stationary black holes emit gravitational waves?
No. But do stationary black holes really exist?
4) Can black holes form quantized bound states?
They could rezonate with their own gravity waves like elementary particles.
5) Can sub-Planck mass micro black holes exist?
6) What happened to the micro black holes produced in the early universe? Did they evaporate; or are they still around in some form?
Were such black holes created at all? In my opinion the only primordial black holes are sitting at the center of quasars and active gallactic nuclei.
7) Is there any link between black holes and dark matter?
Yes, by the same way, like between common and dark matter.
8) Is there any link between black holes and dark energy?
Yes, in remote sense. By AWT the observable Universe is formed by interior of collapsar, which collapses in increasing speed - which we can perceive like accelerated Universe expansion.
9) Can black holes have multiple singularities?
Yes, especially those larger ones. If our Universe is formed by interior of black hole, then every black hole inside it is such a daughter singularity.
10) Can Hawking radiation emitted by decaying black holes give rist to Untra High Energy Cosmic Rays?
In my opinion UHECR's are formed during black hole collisions and merging.