We are debating doing another syndication and locking the money up for 12-18 months, but also want to learn more and be able to jump into small multifamily once we get back. 

Tax consequences are very different as well.The S Corp debate for rental real estate has been beat to death on this forum. 

Now whether it's just replacing the HWH with a boiler unit or replacing the whole thing with a combination system is still up for debate - I'm being told to do the combination because it will be more efficient since I'm paying the gas, but then again this could be someone trying to upsell me.

Would it be best to request an oral hearing and if so what data should I bring to debate in why my assessed value should be lowered?

If personal property, the Realtor's argument is drastically weakened; if real property, the debate goes on.But there is another reason that Realtor's don't heavily pursue their claim.  

How much should it typically cost to do over a roof for a 2 fam in Queens?

@Jeffrey HolstI was debating which way would be quicker for the lawyer, so that is helpful.

Others disagree, but you can read those debates here and decide for yourself.Pretty much the only difference you'll have from a tax perspective is that in an LLC you may have an additional deductible expense for maintaining the LLC with the Secretary of State, an additional expense to file a tax return and more formalized bookkeeping and corporate governance duties.PS - I am right up the road from you in Arvada.  

Also, I see there is much debate as to whether funds need to be 'wet' or whether 1 set of funds can be used for both transactions.  

Many have been a topic of debate over the last couple years due to an increase in the use of these instruments.