I'm planning a trip to Yunnan this September. I know someone who lives in Bazi Village (坝子) in Malipo, which is not far from the Lao Shan scenic area on the Vietnamese border. I would like to visit them - I would be starting in Kunming and taking a bus to Wenshan, down to either Malipo or Maguan. This is where I need help.

Is it likely that I would be able to find a driver/interpreter anywhere in Malipo or Maguan? I would prefer this since it gives me more flexibility. The alternative would be to hire one in Kunming, but it would be much more expensive since it would be such a long drive.

Afterwards I hope to visit Gulin Village (古林箐乡) before heading to Hekou and crossing into Vietnam - but that is just for context.

Any help or advice would be greatly appreciated. Thank you very much!

Car, yes. You can always find a driver for a fee in towns. You might even get a daily rate from a taxi driver. Perhaps your friend knows someone, who knows someone, etc.
Translator, possibly not in Malipo. You will probably find a translator who is willing to travel with you from Kunming, if you pay for transport and accommodation. They will then be able to assist with getting train/bus tickets, hotel, etc.

Try putting a classified ad on Gokunming - Wanted Translator for travel in Wenshan.
I do see people advertising here who offer translation and assistance type help. Possibly uni students. You should get a response to an ad.

Thank you very much for the advice. Posting a classified ad is a great idea! And it's good to know that it shouldn't be a problem hiring a driver even if the interpreter doesn't work out.