1) The IF in assembler is handled by the conditional jumps. JB/JNB for bit checks, JZ, JB acc.7, for arithmetic. Alsu read up on the interesting feature of the CY when executing CJNE.

2) repeat until will be either one of the above or DJNZ

A simple way would be to write some small samples in C and run them through e.g. the free Keil demo C compiler and have a look at the (less than efficient) assembler code generated.

Have fun

Erik