hi there!! thank you so much for the reply and for the help! i really appreciate it!
as for florence's 1st and 5th ending...
to get both of them you have to accept the gun from florence when he offers it to you, this happens after interviewing magnolia about the break-in. i believe you also have to ask about the notebook after seeing the strange writing in it. after this, you have to wait an in-game week for florence to come back to town on the weekend. go to the sheriff's office and talk to him and you can ask him to teach you how to use the gun. the shooting lessons are where the endings take place.
florence 1st ending: once you find out about florence's secret at the shooting lesson (you'll find out no matter what choices you make there), he'll kiss you. kiss him back and that will lead to a sex scene and you'll get the achievement.
florence's 5th ending: do the same thing as the 1st ending but do NOT kiss him back. he will not like this and tell you to get on your knees. do not fight back and get on your knees like he told you. another scene will happen and then you will get the achievement!
now for jak's 2nd ending!
jak's 2nd ending: this one's pretty easy! after talking to him at the saloon for the first time, approach him again immediately after. he'll be surprised you decided to talk to him again, as he thought he scared you off. take this opportunity to flirt with him, and then flirt with him again. at this point, the two of you will go back to your room at the inn for some alone time. then you'll get the achievement!
if you have any questions, lmk!! :D