Another contractor said cheapest and best option is to do gas wall hung boilers (instant hot water) and baseboard radiators in all 3 units, all mechanicals located witin the units.

When it comes to items that I can get replaced fairly easy I usually wait until they break, I have found many instances that various mechanical items last much longer than expected.

I never knew all the back end detail that goes into all of this. i have done a lot of research on the active mechanics of all of this but never the paperwork involved.

The other mechanical and structural ones are mostly known quantities.  

Once we got going on the rehab, we realized that they don't make parts for the window mechanism anymore (company went out of business).

However, after our inspection we are confident that there is nothing structural/mechanically wrong, just aesthetics need to be improved.

My anticipation is that within two weeks I will have the home to a completed framing stage ready for all mechanical to be done inside, the stucco to be done on the exterior, and the roof to be installed.

I'm a fulltime specialized/certified auto mechanic and like my job; yes, "like".

Since you actually purchased the property at the trustee sale, you do not hold a lien, you hold title to the property as evidenced by the trustee deed, which should be recorded immediately to insure title priority.Of course any taxes, tax liens, mechanics liens, or possible future encumbrances as evidenced by lis pendens filings also come with the property.

or is mechanic lien still in effect?