One solution option for Issue-1 is to check the 'Merge result to single file' option in tFileOutputDelimited component properties. Set the property 'Merge File Path' to your file path for maindata.csv. This creates a file with a name of your choice, in the path defined by you, with all the part- files data merged into one file. Optionally you could remove the source directory and/or override target file. Hope this helps.
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