How to pass more than one parameter for Invocable Methods and collect the return value?

You can do this by using an inner class within the same class you have the InvocableMethod. And receive a List of said class in your Invocable Method.

global class ConvertLeadAction {
  @InvocableMethod(label='Convert Leads')
  global static List<ConvertLeadActionResult> convertLeads(List<ConvertLeadActionRequest> requests) {
    List<ConvertLeadActionResult> results = new List<ConvertLeadActionResult>();
    for (ConvertLeadActionRequest request : requests) {
      results.add(convertLead(request));
    }
    return results;
  }

  public static ConvertLeadActionResult convertLead(ConvertLeadActionRequest request) {
    Database.LeadConvert lc = new Database.LeadConvert();
    lc.setLeadId(request.leadId);
    lc.setConvertedStatus(request.convertedStatus);

    if (request.accountId != null) {
        lc.setAccountId(request.accountId);
    }

    if (request.contactId != null) {
      lc.setContactId(request.contactId);
    }

    if (request.overWriteLeadSource != null && request.overWriteLeadSource) {
      lc.setOverwriteLeadSource(request.overWriteLeadSource);
    }

    if (request.createOpportunity != null && !request.createOpportunity) {
      lc.setDoNotCreateOpportunity(!request.createOpportunity);
    }

    if (request.opportunityName != null) {
      lc.setOpportunityName(request.opportunityName);
    }

    if (request.ownerId != null) {
      lc.setOwnerId(request.ownerId);
    }

    if (request.sendEmailToOwner != null && request.sendEmailToOwner) {
      lc.setSendNotificationEmail(request.sendEmailToOwner);
    }

    Database.LeadConvertResult lcr = Database.convertLead(lc, true);
    if (lcr.isSuccess()) {
      ConvertLeadActionResult result = new ConvertLeadActionResult();
      result.accountId = lcr.getAccountId();
      result.contactId = lcr.getContactId();
      result.opportunityId = lcr.getOpportunityId();
      return result;
    } else {
      throw new ConvertLeadActionException(lcr.getErrors()[0].getMessage());
    }
  }

  global class ConvertLeadActionRequest {
    @InvocableVariable(required=true)
    global ID leadId;

    @InvocableVariable(required=true)
    global String convertedStatus;

    @InvocableVariable
    global ID accountId;

    @InvocableVariable
    global ID contactId;

    @InvocableVariable
    global Boolean overWriteLeadSource;

    @InvocableVariable
    global Boolean createOpportunity;

    @InvocableVariable
    global String opportunityName;

    @InvocableVariable
    global ID ownerId;

    @InvocableVariable
    global Boolean sendEmailToOwner;
  }

  global class ConvertLeadActionResult {
    @InvocableVariable
    global ID accountId;

    @InvocableVariable
    global ID contactId;

    @InvocableVariable
    global ID opportunityId;
  }

  class ConvertLeadActionException extends Exception {}
}

Original Source: https://developer.salesforce.com/docs/atlas.en-us.apexcode.meta/apexcode/apex_classes_annotation_InvocableVariable.htm

If you have any doubts on how to implement this feel free to comment/ask.