SRL has much of the undetectability programmed into it. There is a random amount of wait time in between a mouse move and a click. The main factor is the change of colors. Are these colors changing enough that we need to use autocolors, or can we just put a tolerance identifier. The first thing you should watch out for is standards. Standards will make people able to look at your script and think it looks professional, not some person who enjoys putting caps lock on and putting 5 spaces in between each line. This is just the bare basics. If you want any tips, just send me a PM.
To answer your other questions.
Scar with SRL is safe.
SMART works (afaik)
Yes, mainly molly and some others (its in the SRL Public SVN forum I believe).
If you want to learn about standards, visit my tutorial in my signature.
Formerly known as Cut em2 it