Java Moss can easily be attached with thread, but that does create risks for Otocinclus catfish and other smallish suckermouth cats - I have lost small cats due their getting trapped in the thread and being killed. I no longer use thread in any tank to house such catfish.
Unless you have a significant algae coat on the glass and wood, the tank is too new to support 6 Otos. There really are best only added to mature planted tanks. Without significant green and diatom algae on the glass, plants and ornaments there will not be enough food to support them - especially that many. The small Farlowellas and the OTOs will also compete for food. I am not at all sure the tank is ready for so many specialized feeders.
To me your total stock seems quite heavy for a 45. Is the biofilter able to support that many fish in a brand new tank? That stock list is more than I would use by quite a lot.

