>Warning[202]: Argument out of range.  Least significant bits used.
>0008 301B           00031                 MOVLW   11111b

It doesn't understand you are giving it a binary number. You should say:
            MOVLW   b'00011111'


>Message[302]: Register in operand not in bank 0.  Ensure that bank bits
>are correct.
>0009 0085           00032                 MOVWF   TRISA

PICs can't address registers above 7F directly, and TRISA is 85, and the
assembler is telling you it is addressing 05 or 85, it doesn't know which.
Which one depends on the setting of bit 5 of the status register (this bit
is usually referred to as "RP0").

In other words, of the eight bits you need for a register's address, you can
only specify the lower 7. The eighth bit is ignored, and RP0 is used instead.

To make sure that you are really talking to TRISA, you would need to do this:

           movlw   b'00011111' ;the direction pattern you wanted
           bsf     STATUS,5    ;set RP0 to the 80's
           movwf   TRISA       ;move w into TRISA
           bcf     STATUS,5    ;switch back to the lower bank of registers

You'll still get the "Message[302]: Register in operand not in bank 0.
Ensure that bank bits" warning, but ignore it or tell the assembler to
suppress it.

Most people will tell you that changing to register bank 1 is not needed,
since there is a perfectly good way to do just what you wanted. I'd do it, too!

           movlw   b'00011111' ;your bit pattern
           tris    5           ;5 is the address of port A

This will give you an assembler warning, but ignore it. The tris command is
still valid and you should use it whenever you want to.

Cheers, Bob