grids to trim,

hello,
i have some questions, sorry if these are already exist.

i am trying to make structural facade by lunchbox.And i learnt all i know from your discussions.

first question is; can we select the surface which we are going to make it structural.When i select it i have always waste grids .If we can not; is there any short way to trim ?i do only manually.

and for the members of grids, is it posibble to manage them as an angle? or lenght?
how can we see all the informations how long? and what angle?

i know all these are very beggining questions.but i would appreciate if anyone give a hand.


thanks,
ecem