Have done all of the above and now have somewhat stuck to monofilament for direct pull lines. However, I do a few tricks. I use typically about 20 pound line. I take about a 5′ length of it and place one end in a vice and grab on to the other end with a pair of pliers and pull it hard. This is the pre-stretch that gets rid of alot of the initial stretch. I set the lines up fairly tight onto the timer.
As far as attaching them, I like to use the little rings that Hank of Texas Timer sells. I take a 1/8″ length of aluminum tubing (the size will be either 1/16″ or 3/32″ diameter, which ever will allow two diameters of the monofilament to pass thru) and use that as the ferrule. So, slide the little alum tube onto the monofilament, run the loose end thru the ring, and snake it back thru the tube. Crimp it with a pair of pliers and add a very small drop of CA. That should hold it for ever.
Now, if you are doing a pop up stab and the line has to wrap around a pivot point, you need to make up a composite line. If the line is 2 feet long, the use a foot of monofilament and a foot of dacron fishing line (the black stuff that looks like it is made of cloth). This stuff will go around the pivot easy without kinking like monofilament plus you have a little bit of stretch from the mono. Use the same tubing idea and a bit of CA and you are done!!