Review of EESA about any income based entitlement

The DWP have written to me about Income based Employment and Support Allowance. They have sent a 45 page form ESA3 (IBRD) 04/18 with a four page covering letter. They are asking for information from 28 February 2013 to 16 August 2017.
The official government website www.gov.uk gives information about benefits.
Would this take precedence over information that the DWP include in their ESA3 (IBRD 04/18 form, for example, the relevancy of being in hospital and my income.
How can I get hold of the information about income based Employment and Support Allowance on these two dates and what and when changes were made between these dates?
There is a question about savings over £16 000. If they are asking about income base Employment and Support Allowance, is the net income from any savings more relevant. Also savings like shares can fluctuate from transaction to transaction. If I need to to send information about capital in savings (not income or as well as income), what is an acceptable time period for a mean average maximum? Five years? One year? Six months? Three months? One month? Four weeks? Two weeks? One week? One day? One hour? One transaction? Or?
Part of the declaration includes "I declare that I have read and understood the notes at the front of this form, the information I have given is correct and complete and I have included all my income and savings . . . If I give false or incomplete information or fail to report changes in my circumstances promptly, I understand that my Employment and Support Allowance may be stopped or reduced and any over payment may be recovered. In addition, I may be prosecuted or face a financial penalty . . ". This, to me, is very heavily worded.
My contribution based Employment and Support Allowance stopped when I started receiving a state pension. Also, I receive Disability Living Allowance.
Stress can be a trigger for a relapse in health condition. At one time, I was in hospital for fourteen months.
I am finding getting information for the ESA3 (IBRD) 04/18 form distressing and difficult. An example is the questions about when II was admitted to and discharged from hospital and to and from a care home. My GP states that she may not have records going back to February 2013; my local hospital records have been transferred to another hospital - I have been given two departments to write to; when there was no bed space locally, I was transferred to another hospital three train journeys away, but they may not have any local records; another care provider is asking for authenticated identity like a driving licence (I am not allowed to drive) or passport (mine expired several years ago) as well as proof of address through a utility or council tax bill (I pay mine by Direct Debit or Standing Order). But, how does time in hospital or in a care home affect my income or my savings?
I receive both components of Disability Living Allowance.
Does anyone in this forum have comments and such like to make about any of the above?

your gp really should have all your records - certainly back to 2013 - that is not that long ago

this form will not affect your current situation
it is about their mess up of not paying some people what they were due

re. savings you will need to list all types of accounts and the amount in them - NOT just the interest/income
if you had over £16k in savings/accounts then there is nothing owing
the best thing to do is fill in as much as you can, and like Gordon says, give an accompanying letter to cover anything else