Ingest user_properties other than user_id and device_id using NodeJS SDK

I am using NodeJS SDK to insert events and event_properties using HTTP API v2, and user_properites using identify

My sample code block looks as below

import { Identify } from '@amplitude/identify'

import * as Amplitude from '@amplitude/node'

const client = Amplitude.init(amplitude_api);

const identify = new Identify();

const payload ={event_type: eventType,

device_id: row.deviceid,

user_id: row.userid,

event_properties: row,

event_date: moment(row.timestamp).format('YYYY-MM-DD'),

timestamp: new Date(row.timestamp),

update_timestamp:new Date().toISOString(),

context: {ip: row.ipaddress},

// "user_properties": {

// user_id: row.userid,

// device_id: row.deviceid,

// partner_id: row.partnerid,

// slotid: row.slotid

// },

}

identify.set('user_id', row.userid).set('device_id',row.deviceid)

const userProperties = {'partner_id':row.partner_id as string,'osname':row.osname,'devicetype': row.devicetype}

identify.append('partner_id',row.partner_id as string) 

const identifyEvent = identify.identifyUser('user_id','device_id')

client.logEvent(identifyEvent);

client.logEvent(payload)

Questions:

1. It looks like I don’t have to use identify API for user_properties as we can pass these with events itself (client.logEvent(payload)) . Is this assumption correct. I have commented the user_properties in my code for now but I could get the user_id, device_id, partner_id and slotid inserted into user_properties of Amplitude just fine. Is this a good way to implement this or should I have to look at other ways like insert into identify end point before event endpoint
2. If I need to user identify I could only pass user_id, device_id into the “const identifyEvent = identify.identifyUser('user_id','device_id')”. Any third value is not allowed here. I also tried to append to identify using “identify.append('partner_id',row.partner_id as string) “, doesn’t seem to work as well
3. So if I need to use identify how can I ingest more user_properties other than just user_id and device_id
4. How can run my segment reports based on event_date instead of insert date in the default date option available. Screenshot attached

   

5. How can I filter using between clause in for dates or any other attribute in where condition. Screenshot attached

6.