So I'm starting a campaign here in about 10 days, for 6 players. Usually we will only be at 5 players due to two players having work schedules that clash on occasion. Here is the party makeup. They have decent stats all around +10 to 12 stat mod characters characters
Tiefling Fighter CG
Half Elf Witch CG
Human Monk (Cant always make it) LG
Human Rogue (Cant always make it) TN
Tiefling Infernal Battle Sorcerer CN
Human Druid NA
Since this is a bit larger then the AP recommends I was thinking for the sewers to increase all the encounters by 2 monsters. and for the Rescue operation making Shanwen lvl 3 and increasing his stats to be closer to a actual player. Am I on the right track for increasing the encounters to be challenging? Also I was thinking of Adding the advance Template to the Shadow Beast, and maybe the Giant template to make it a bit harder. And any suggestions or advice on running the adventure would be appreciated.