Has anyone done a syndication / joint venture with a TIC investor?

If it's not enough to do something by yourself, try a joint venture w/ a trusted partner.

Cash-out refi before selling so that your capital gain is under the $500k cap for joint filing.However, having the property listed for sale will hinder any refinance options.But if you C/O refi and then list the property for sale after, then you shouldn't have any issues.

Can't comment on a pre-nup, but I know couples that rather than giving their new spouse access to bank accounts, open up a joint account and then both transfer money into that.

If using polyiso or extruded polystyrene (exp)  not expanded polystyrene) will give you an air barrier and moisture barrier if the joints are full sealed.  

Also if you file jointly you can qualify as a Real Estate Professional and take the losses - read more about that in BP Blogs.

There is a law that allows spouses to elect to be taxed as a joint venture if the business is not operated through an incorporated entity like an LLC.

We file jointly.

If your LLC does not file it's own tax return then all activity of the property was reported on your personal joint tax return. 

You need to pull the current deed and determine if they held as tenants in common or joint tenants with the right of survivorship.Also the use of quitclaim deeds very much depends on the location of the property.