A 1D file should just be text and can be read with any text editor (emacs, nano, vi, cat, etc). You can translate it to a CSV using a number of tools (emacs, sed, tr, excel, R).
However, there are a number of AFNI programs for dealing with 1D files. 1dcat can give you individual columns, rows, etc or add columns to a 1D file. 1deval can perform calculations or functions on 1D files. You can also use ccalc for general command line calculations. Also worth noting is that many AFNI 3d* programs will perform calculations on 1D files. If you have a file with multiple columns, you can calculate the mean of all three with:
3dTstat -mean -prefix stdout: file.1D\'
