1) Tartan vs. plaid: Nowadays they are often used interchangeably. Based on the context, they may refer to the cloth with plaid pattern or to the pattern itself.
Please, look them up on online Cambridge and Merriam-Webster dictionaries. I didn't post the links here because then my reply might not get published.
2) Committed may have several meanings but considering your question, in here:
Committed means performed/done.
Partnered means became a partner of.
Example: This company partnered with that company and committed years of careful researches.
* In many cases "to commit" is used for an illegal or immoral action; for example: committing suicide.