the sping lock tool is easy to use. it slides over the fitting and the groove in the tool slides into the spring lock ( you will see the spring) when it's pushed in just pull the fuel line and it shou;d come right out.
if your taking your injectors out make sure you spray the o rings with some spray lube that will help the o rings slide into the bores
Any auto parts store has them. Get the cheap plastic ones (it's a kit with 6 or so small plastic disks) they are only about $6 to $10. Don't buy a fancy set for more, it's not worth it.
You need the tool for not only the gas line to the fuel rail but also your fuel filter.