You don't need a super expensive multimeter to work on bikes. The $6 one from Harbor freight will work fine, but the lead are short and the wire inside is thin.

I often use the AstoAI one from Amazon that runs about $11. I picked this one because I didn't need a crazy meter and It had a decent clamshell case for it.

I combine the meter with this kit . . . super sharp / low profile meter leads are a GOD send.

As for your connectors. I've never used those personally, but the waterproof bullet insert type that have a male/female end are often found on bikes from the factory.