I am looking for thoughts on whether I should be proactive with replacing a 20yr+ old roof (missing shingles, multiple layers, looks terrible) and a 25yr+ old hvac.

I am risk averse and if I were to purchase, I would tear down to the studs and do a full rehab {this would include getting rid of asbestos shingles and insulation).1) I have done a ton of research and it appears as if getting rid of asbestos is very DIY able assuming you spend money on the safety equipment and use it properly. 

I would like to get a quote for insurance.6 unit single story building.  1960's construction, all brick exterior, cement slab, and new asphalt shingle roof. 

Lastly, is it possible to put a “seal” on a current shingled roof, should there be any leaks?

Google street view doesn't show you that....or ends up that street view picture was from 2013, and when you drive in 2024 you find someone has dumped 1000 houses worth of used shingles there.Be careful and be smart. 

The owner must grant such access to computerized orother electronic records & to any computers, facilities & mustprovide any information or assistance needed to access the records.5.

An asphalt shingle roof often lasts 25 yrs, so you need to reserve $27/mo EVERY MONTH for 25 years to have $8k available in 25 yrs.  

I have access to loans at 2%.I have had multiple contractors tell me that my roof will be eligible for an insurance claim due to shingles with storm damage.

Unlikely.80% of our landlords use Excel or bar napkins or some combo. 60% of our small business owners are single-shingle "one man bands," and they too use Excel.QBO, Waveapps, Freshbooks, Stalebooks, SloppyBooks, Xero, One and all the others are nice to have but not must haves until you have several rentals or complex rentals (such as a strip mall or something).

They (ins co's) wanted our industry (Roofing) to come up with better-longer lasting materials, like Class 4 shingles, so they wouldn't have to pay for replacing shingled roofs so often Fine, it happened.