What means this line in assembler?
__user_libspace: 0x10000AE0 ES813Bf3 ADD R3, R1, #0x0001CC00
instruction at the addr 0x10000AE0 called a ADD order to add value in R1 to R3 - but what about the #0x0001CC00?
R2 is no register, it is a address in the RAM, isn't it?
No, it is not. The ARM architecture is a load/store (also known as RISC) architecture, which means that data processing instructions cannot work with memory contents, but with registers and constants only.
R2, in this case, is a flexible second operand. What exactly that means is also explained in the ARM assembly docs.