What's up with CUPS?

i am trying to set some defaults (print at actual size and don't rotate) which /seem/ like they should be defaults but aren't. and between the printer interface and my various OS's and my brain being filled with other stuff i have had a hard time with this. my recollection was that in Snow Leopard this was a terminal command but now in Lion and ML i am reading up on CUPS.

1. can anyone tell me what the reason is that i need to use CUPS? i mean, it is a consequence of the complexity of printing and or the relative lack of development in mac os of the printer dialog interfaces? the variety of printer manufacturers? if understand why i am using it it may help me to get it done.

2. can someone remind me on how to implement the two above defaults like if a dumb monkey distracted by a banana had to implement this? i am reading the online documentation and it appears this is a command line set of entries that i have to enter after getting into terminal (or an online resource??) but also the documentation seems to state specifically (printed page 8 of 10 in Command-Line Printing and Options under Standard Printing Options) that the default for size is "to use the size specified in the file" which /seems/ like it is saying that scale to fit should not be the default which of course it is.

anyway, these command line interfaces get my head spinning especially if i don't understand what the default is or why i am using it but at the same time this is an functionality i would dearly love to click a LOT less when using.

TIA for anything constructive.