1. All triggers get better with use. They naturally polish edges through use. Does it make a big difference? In my experiences no. To make a big difference, trigger work/rework or replacement needs to be done. In a Handy, replacement is not an option.
2. There is a built in safety, the transfer bar. Even if the hammer drops, with out having the trigger pulled back, the hammer will not strike the firing pin. Having said that, I stopped around the 2 - 2 1/2 pound range. I stopped there because it felt good to me and I did not want to over do it. Once you take too much off, you can not put it back on. Transfer bar or no, it would be unsettling for me to pull back the trigger and not have it set. It gave me a crisp pull and it does not feel heavy.
Take your time with it. Take a little off, reassemble, try it. Keep doing it just a little at a time. I did the drop test and the struck the side of the receiver with the heal of my palm hard; when I was getting close to make sure I did not go too far. BTW I do not know if I missed it in the instructions, but I had a devil of a time putting the trigger group back in the first time. I eventually found that I had to pull the trigger back as I inserted it into the receiver to get it all lined up right. After I figured that out it was easy. I used a piece of heavy solder cut to the correct length for a slave pin. It does not have to be stiff, because it only holds things in alignment until the real pin goes through. I also did not reinsert the pins all the way back in while working on the trigger. I only pushed them in enough to keep everything where it should be. I was afraid of rounding out the hole and not having the pins stay put later. It also made the disassemble and reassemble easier while doing the fitting. I only drove them home after I was satisfied with the results.