Ask a landlord-tenant lawyer and get answers ASAP
can each person sue individually for retaliation or as one suit together.
Response 1: As one suit together.
Also, can each issue where he delayed doing anything be considered retaliatory
Response 2: No, unless you have concrete evidence that the Landlord refused to make the repairs to get back at you for exercising your rights as a Tenant.
Yes, you can file Small Claim to recover your expenses.