asm question's

[gur milstein]

helo every body.

i have some stupid question's.

1)when should i asembeld the pots,after soledering the board or
when soledreing all resistors ?

2)the pots which should be connected to +/-15 and gnd ,to where 
on the pcb should i connect them,the input power holes ?

3)can a BF-256 or TIS-74  replace the 2N4391,and should it be the 
same in the leges order ?

thanx
Gur Milstein