Yes the A380 will be able to taxi its self onto stand 12. There are a few taxiway restrictions but its mostly fine.
As for how aircraft park, read the Visual Docking Systems section of this:
http://www.caa.co.uk/docs/33/CAP637.PDF
Stand 12 will have SafeDock
B-pier (T1) has mirrors and PAPA
C-Pier has PAPAS