Due to recent security frauds and banks not covering losses adequately, apps like Zelle may not currently be the best option.

I look at the tenant's financial situation (income security) as a very important part of the property analysis. 

I found this on their web site:Our company Tax Alchemy provides tax planning and implementation services as a flat rate fee based on the tax strategies needed to reduce your tax bill.

I have prospective tenants who signed a lease on 31st of October and paid security deposit same day.

An estoppel certificate is a form you have the tenant sign that confirms their lease start date, the amount of their security deposit, and other things.

I used furnished finder and keycheck to find tenants, screen them, and collect rent/security deposits. 

Do you have to keep the security deposit in a separate account?

This needs to be highlighted in the lease and acknowledged by them.Security Deposits: You can’t use their security deposit for routine cleaning, but if they leave things in bad shape beyond normal wear and tear, it’s fair game to deduct cleaning costs.I’d start by having a straightforward talk with them about the importance of keeping things clean for health reasons and property preservation.

Consider a cash-out refinance or a small business loan to fund these repairs and secure the property long-term.

Anyone have a good web developer that has room for clients!?