Are there any reliable software that you guys use for this? 

If there are multiple doors then I'd just lock it in a way that makes the door unusable 

Having a reliable lender with experience can help guide you to the best options for your qualifications, however at a minimum if trying to qualify for a conventional loan you'll need at least a 620 FICO mid score, other options are FHA using lower scores.

Hostaway is not the cheapest software out there, but it has the most stable connections, reliability and 24/7 support. 

A Minut sensor might be more reliable for detecting smoke presence, keep in mind that it may not differentiate types of smoke.

I think most of what you are asking is impossible for anyone here to reliably answer without more information and you should probably consult an attorney if you think it is worth it.

Spend LOTS of MONEY on mass marketingThe "rate locked affect" is limiting a large portion of the market and stopping transactions from happening.

There is a lot here that he needs go over, such as are you cashing out, looking to lock rate, is there pre pay, do you want community or agency?

Is Rabbu reliable? 

How do you guys find reliable cash buyers for your deals?