If I own the LLC but have a separate agreement addendum with a partner for a particular property, do we each claim a share of the property expenses and I claim the entirety of business expenses outside of the property?

The following is based on data for the entirety of Prince George's County. 

Staying active on these forums is another good way to see who is a syndicator and then you can reach out and directly message them to chat a bit.Joe Fairless also has a great podcast series that goes through the entirety of buying a multifamily property via syndicaton. 

IRR is designed to calculate performance of an investment in its entirety (from inception to disposition).

This more relates to when people choose not to depreciate the ENTIRETY of the rental (not improvements/repairs) on the thought that they won't need to pay recapture.

Because you've been using the entirety as a rental you must do the 1031 on the entire amount if you don't want to pay any tax.So to completely defer all tax you would need to purchase at least $700K (net of closing costs) and use all $350K in the purchase or purchases.  

Sounds like you've met the use tests for the entirety. 

Being there for the entirety of the project is a waste of your time...maybe checking in every now and then (once or twice a day) would keep them honest and allows you to monitor progress. 

So, if you have hard money, or a bank loan that will close and pay in it's entirety it shouldn't matter.

Yes, you can buy 50% of a property from any joint owner who owns 50% or more -- other than a husband or wife who hold title as tenants by the entirety.