Question about applying for loan

There is second-hand manshion that our family are really interested in purchasing and already book to see this weekend.

Regarding loans, just like many advices, we should try to get the biggest loan the bank can give and spend the lowest for down payment. We already read around for basic knowledge, but apologies for the newbie question to reassure our understanding, how does it work in general?

Do we apply to as many banks as possible with the highest number we are comfortable with, and during the final screening give them annual tax reports, payslips, investment reports, and so on…?
Then let them decide whether 1) they grant the whole loan amount along with their interest offer, or 2) perhaps they counter offer that they can only give 70% based on my profile, or 3) reject my application completely?
Does it help to also give spouse's financial reports? Most likely not going to be considered for decision making, but I was thinking nothing to lose.

Appreciate your thoughts!

by MinnMaxx