‘[…] is it possible to add some kerning and marks lookups to this font […]’
In DTL OTMaster one can export the layout features, edit/add stuff and subsequently recompile the tables.

One can use the ‘Import…features’ functionality for instance for the positioning of marks in Arabic fonts. A (standardized) features file containing the necessary information can be imported and subsequently the mark attachment points can be edited interactively or numerically via the Tools –> ‘GPOS’/’GSUB’ Table Viewer for the correct positioning of the (mark to) marks.
FEB