Double cosplay help

[Hyunah]

So Im making both a new world Usopp and Luffy cosplay for an upcoming con. So my questions are as follows:

-What fabric should I use for Usopp's pants?
-What fabric should I use for Luffy's shirts?
-Where can I get Luffy's sandals?
-Shirt patterns for Luffy?


Refrence pics
Usopp one
Usopp two
Luffy oneLuffy two