Hello @Eisfee,
and welcome to KNIME Community!
You should be able to use String Manipulation (Multi Column) node to replace multiple String Manipulation nodes with same expression. (Hope you have found and using removeChars() function for removing spaces.)
Regarding second part unfortunately there is no Rule Engine (Multi Column) node. However if all columns are string you can try with String Manipulation (Multi Column) node again and regexReplace() function. Might work. Alternatively you can use Column Expressions node to have it all in one node as you can write multiple expressions in it. Lastly approach I often use if Unpivot → apply Logic → Pivot. See here more about it:
Hope this helps!
Br,
Ivan