Family visitor visa few questions

Hi All,

I am filling online application for my parents and have few questions.

My parents history

Passport: Pakistani
Home Country: Pakistan
Current Country of resident: Canada (living from last 1.5 years)
Canadian visa status: Permit Resident (but don't have passport yet under qualifying period)
Country they are applying visa from: Canada
Finances: My parents, both have approximately $2000 maintained in their accounts from last 3 months

================================================
Passport and Travel Information
================================================
UKVI: Please Enter Details of what permission you have to stay in this country
My parents are based in Canada and they hold Permit Resident status. Should I mention Permit Resident in the field?

UKVI: Have you ever had any previous passports [or travel documents]
They do have previous passport but some of them are lost. They don't have passport number and there is no police report. Should I disclose lost passport? If yes, then should put in fields?

UKVI: Are you travelling with anyone?
I will apply visa for both, none of them have valid UK visa. Should I mention that in their application that they will be travelling with each other? There is similar question in section 3.
================================================
Personal Details and Travel History
================================================
UKVI: Have you been issued any visa for the UK, UK Overseas Territories or Commonwealth Country in the last 10 years?
They have Canada visa for the settlement route. Do I need to mention details in this section or there is no need to mention it as they are applying for UK visa from Canada?
================================================
Family Details
================================================
UKVI: Will your spouse/partner be travelling with you?
In section 1 there is a similar question if you are travelling with anyone and its being repeated again under section 3. Should I add information on both section or just under section 3 or 1?
================================================
Employment and Income
================================================
UKVI: Do you have savings, properties or other income, for example from stocks and shares?
My parents have saving of $4000 in their joint bank accounts. They don't have properties or other savings. They are currently living with my sister and brother in law and all day to day expenses are covered by them for e.g. food, house rent, etc... The health services are provided by government, so virtually they don't have any living expenses.

Should I mention their account's savings?

Can I mention None in cost of living and expenses? For e.g.

Source of income : Cheque coming from govt or do I need to show brother in law bank statement or letter from him?
Cost of Living: None ( As living with family)
Expenses: None ( As living with family)

Their UK visit will be sponsored by me which include flights, accommodation, food, etc...

Can UKVI raise question on their finances?
================================================
Additional information
================================================
I add below information in the textbox.

I intend to visit UK during summer with my husband to spend quality time with our son and daughter families. I intend to visit my daughter who recently gives birth to baby boy and also plan to visit country side and explore British culture.

I intend to go back at the end of my visit to join my daughter and family and also to complete Canada residency qualifying period.
I am house wife and my son is fully supporting me for UK visit. I will be staying with him, so there will be no accommodation or living expenses that I would incur.

I am applying for UK visa along with my husband. The original documents are submitted with my husband application and accessible easily.

I trust the information I have provided is satisfactory, however if you have any questions or queries or require additional information regarding any aspect of the application, please do not hesitate to contact me or my son.
================================================

I would appreciate reply from senior members