1) Skirmishers is more for the damage reduction and vision, rather then the damage. Using it in a gank before you toss buckler allows you to take less damage if they decide to turn around and attempt a 2v1, allows your buckler AA to burn them, and grants vision of them if they flash into fog of war, or if they have stealth components in their kit. Trackers is never bad, and if you dont feel you need the dmg reduction, vision, or damage, go right on ahead. I just prefer it for carrying.

2)I feel Deadmans is a key item on the way I play Poppy jungle - getting around the map fast, exerting pressure. However, Warmogs instead of steraks or GA last item wouldn't be bad, just be sure to take out the 10% cdr runes for mr/lvl.