do you have down payment + closing costs + rent ready costs + reserves + savings + emergency fund? 

They handle payments, payoffs, and year-end tax information. 

Lender can foreclose due to property taxes not being paid, insurance being lapsed or payments not being made on the loan 

Its probably because they don't want you contacting the applicant to cut them out of the deal.

I heard in a podcast that the inventory of homes is back to pre-pandemic levels in some areas and I have noticed more price cuts in general -  but that's mostly the greedy sellers trying to list their homes for way more than the current market value of the home.

Buying under an LLC shifts the type of loans you would be eligible for, and likely rules you out of considering a house hack or using an FHA/VA loan, but opens up different funding options if you have the capital for a larger down payment.

If this is a conventional loan then all documents pertaining to income,current mortgage and insurance, etc. if it is a DSCR refi you will need much less. 12 months of payment history, 12 months of rental income, insurance, bank statements and whatever else the lender may require. 

I'm a landlord and I will have a new tenant since my old tenant don’t want to renew the lease, So with this new tenant I want to use the auto-pay debit from tenant's bank account and send it to my account, in order to avoid late payments and stress.

You all sign a contract and agree on scope, fee amounts and WHEN payment is due and abide by the agreement. 

Most guru's try to create short-cuts that don't exist.