Some questions about Operators and UI

Hi,
I’ve recently started to work on blender source code in order to achieve a new set set of tools for unwrapping: it’s basically an align/distribute operator.

So, first of all, I’ dont know exactly where to add new code, firstly i’ve added it in “uvedit_ops.c” , but after looking in the code, and since i need to work on UV Island i moved to “uvedit_unwrap_ops.c” since it have access to “ParamHandle” struct and uv chart. Is this this the right choice??

Secondly, Since these are at last six different operator for alignment and other six for distribution, i don’t know if it’s better to write one single operator with an enum prop for each different “tool(align center, align right,…)” or write each tool as separated operator with it’s own name (" UV_OT_align_vertical_center, UV_OT_align_horiz_center, and so on…). I ask this because in UI this two different “ways” are displayed differently: the first, by using operator_enum() i get the buttons in different row, instead the second by using only operator() i get the effect i want: similar to this from inkscape
http://i2.wp.com/www.chrishilbig.com/wp-content/uploads/2013/02/Inkscape-align-and-distribute-pallet.png?resize=340%2C431.
So what is the best method??

Another problem i have, is that i can set default enum value: when i start blender the default value in the UI menu of my prop, is not displayed…