bifold or trifold brochure? please mention.

Size?

Trifold would be good
Sizing would be a double sided A4- business card would be the standard sized one

To clarify, the brochure can be single sided print. If you need more room, please feel free to use up both sides for the tri-fold

The membership card would be a print out the standard size of a business card (approx 89x49)