Both these lines...

If (BUTTONS & %00001000) = 1 THEN Menu_1 = 1
If (BUTTONS & %00001000) = 0 THEN Menu_1 = 0

Can be simply replaced with...

Menu_1=BUTTONS.3

Which means go take Bit 3 of variable BUTTONS and put it into Bit variable Menu_1

Oh... and Yes, bit manipulation like this IS described in the PBP manual...

You can also do things like...

Menu_1=PORTB.3

Which means go read PortB.3 and put that into Bit variable Menu_1

And you can also go a stage further...

MenuButton var PortB.3 ' Declare this at the start of your program...

...thereafter anytime you want you can simply ask...

IF MenuButton=0 then Goto MenuEntry

Which is the same as asking...

If PortB.3=0 then Goto MenuEntry

and so on, and so on, ad nauseum...