I'm sorry if I'm missing or repeating anything, but I'm trying to help, but short on time, so only skimmed the messages.
SSIS does not like spaces in worksheet names. When you create one on the fly, it always replaces spaces with underscores. If you will be repetitively getting new Excel sheets to import with names, rather than manually renaming them, you can use an expression task to search on the space and then replacing it with an underscore.
Good luck. I hope this helps.