I use a tool called Dealcheck that does all the calculations for me.

@Tim MonistereBP has a rent estimation tool.

It is probably more DIY though where they provide basic tools, do basic review as the broker or something. 

Then use whatever tools you have at your disposal (Skip trace, looking for numbers on LLC docs, looking for their number on MLS if it's an owner/agent, send post cards to their tax mailing address, etc) to get numbers for the managing membersHave a script you can use to call them and ask them if they are buying, what they're buying, price points, rehab level, neighborhoods, etc.The good thing about this strategy, although it's a lot of work, is that you are connecting with actual buyers who have actually recently closed deals

Make sure you check out all that this site has to offer.Alerts can be really helpful too: http://www.biggerpockets.com/alertsThe site has quite a few tools that can be helpful for new members.

Google is also a wonderful tool.

I've invested in multiple softwares, tools & market research to help me locate property and owner info (such as Propstream, Batchleads, etc) but it's not providing the returns I know I could be getting if I was directly tapped into the MLS.

I also realize that our business is one of reputation so being diplomatic and asking nicely and respectfully goes a long way when I am trying to do things for my clients that might be considered an inconvenience to sellers or other agents.Communication is also a huge part of a good agent’s tool belt.

Because of that and that we would like to store our tools there when we move in -- we would like to limit access -- though we are okay with the seasonal tires.Unit 1 is the only unit whose circuit breaker is in the basement and therefore require access by law.

First lien HELOCs are the most powerful investing tool I know of.I think I'd look for another bank or institution that offers the first lien HELOC and compare costs, but you are absolutely onto the right product so in general, pursue that with determination.And to avoid assumption, check out velocity banking if you haven't already.