1.) If vigilante tries to strangle and is role blocked does that count as ability failing? Because if they're role blocked then it's not like the vigilante tries to strangle because they don't even get the chance. Wording makes it confusing because of how role blocking works.
If you roleblock a player who was about to use an ability, that ability fails. So, in your example, the Vigilante fails to strangle someone, and thus is called out. As always, uses are still consumed even after failure.
2.) Do experimental traps stay active after the night they are used, if the experimental trap does not catch anyone the night it was originally used? Or does it disarm itself if nothing happens the night it was placed?
Traps only work the night they are set. This is clarified by "this night" in the ability text. I added it one more time there to make it more obvious.
3.) What happens if strange pills is used on someone who gets killed by an ability that makes noise? Like if a vigilante shoots someone who was given strange pills, do both the vigilante and the recipient of strange pills die?
Yes, both die, as Strange Pills have a higher Priority than Assassinate.