You can reduce your tax liability significantly if your portfolio could benefit from a cost segregation analysis.

Such would mean that regardless of whether or not there was an LLC involved, from a liability perspective (if such were to ever arise), there would be no distinction between you as an individual and the business entity.

If I did it wrong, would it be a dangerous liability or something?

Larger liability for errors, possibly a lot of expenses.

You are creating some big liability for yourself in doing this, so make sure you do it right.  

Here is my opinion so far:US:- 30yr fixed principle repayment mortgage, so actually build equity assuming 0 appreciation- rates around 4.2% right now (also get a small discount through work)- first 4 properties 20% down, then 25%- can deduct all expenses plus depreciation- I have a large liability in USD (student loan) so would be good to have a USD cash flow and avoid FX riskUK:- interest only mortgages with 3-5% fixed rates for 3-5 years...then need to refinance (which can be expensive and unpredictable...also interest only so relying on appreciation)- however, interest only improves the cash flow significantly as the mortgage amounts are tiny- 25%+ down- slightly less tax friendly, it seems- much less space, higher population density and growth...points to higher average appreciation potentialDoes anyone have any thoughts?

The property tax is not much and I imagine liability insurance wont be as well so its not a huge problem to hold it for a while if needed.The biggest cost would most likely be demolishing the rundown building (can be done by hand) and cleaning out the jungle that has developed on the property.Its certainly one of those where its worth to put out a feeler and make an offer and see what happens, especially since I feel the neighborhood is on the "come-up".

They give unlimited liability to all partners for their own AND their partners' actions.

Relationship: The Parties hereto shall not be deemed to be Partners or Joint Ventures and no Party shall be liable for any other Party's commitments or liabilities resulting from execution of this Agreement.

Do they have any liability?