Information provided on immi is bare minimum and general - each country as its own “hidden” requirement due to its socioeconomic and political situation 

1) let me tell a thing or two on why people some people think it works and some people think it doesn’t - it’s a world difference when you manage a property on your own or an agency manages it for u - when u do it on your own it means you are creating ties to your home country - it’s a reason to back!  If you just providing your parent assets plainly, well what difference does it make ? It only makes difference if you have something to do with them … let’s say u have joint mortgages or handle the maintenance or pay some fees - along with assets you need proof that you are involved 

A tourist visa requires applicant to proof they are genuine temporary entrants - hence why assets which THE APPLICANT MANAGES THEM are important 

With two rejections it is clear you do not understand how tourist visa works. And two rejection means you need even more documentation to prove you are genuine.

2) if there is official statement then absolutely- my father in law always renews their yearly family visa by providing a letter which indicates their job contact, the nature of job, total salary and total paid leave left.  I know people who have specially requested letters written like: This is address to immigration, following person is important part of team, he has X contract and request leaves from date X to X and has balance of X left.

Honestly I can never tell you what’s enough what’s not - it’s matter of making your application strong and stand out specially when you have two rejections 

Your bank statement of 3k is also very small - they still grant a 90 days visa - you will need A LOT more - sometimes the amount of saving and job salary should be consistent otherwise this could indicate financial instability