Setting GPIO on Raspberry PI using a function

[nilamo]

none of my GPIO are being set, if I use print (MUX1shift1_Y0) I get the print out of <function <lambda> at 0x73a53810>:

Those are functions.  They don't do anything, unless you call them.  ie: MUX1shift1_Y0 does nothing (like, literal nothing), while MUX1shift1_Y0() will call the function.

Also at the risk of opening a can of worms can anyone explain lambda to me and why I was told to stay away from it?

They're just anonymous functions.  Whoever told you to stay away from them probably said so because they can be confusing to newbies.  In python, they're a little underpowered compared to most languages which have them, but for this case, they're perfectly capable.