If I am cautious about the big ticket capex items(roof, heat/air), what is the harm in purchasing these types of property?  

This has led to harm to MANY sellers.

Over-leveraging can be just as harmful as under-leveraging.

No harm in ASKING your Lender, is there?

Pretty well accepted premis-a neighborhood of small houses will harm the value of larger homes and vice versa, so you're fine, imo all other things considered equal.

If you are looking to have no friends, family wars and added work place stress go ahead otherwise screen and select applicants only from strangers.

No harm in letting them know you are the designated "property manager".

If they slow a house closing over a lien and they lose they could be in for a rude awakening if you can prove you were harmed, which you can.  

We don’t know any PMCs to recommend in the area mentioned, but since selecting the wrong PMC is usually more harmful than selecting a bad tenant, you might want to read our series about “How to Screen a PMC Better than a Tenant”:https://www.biggerpockets.com/member-blogs/3094/91877-how-to-screen-a-pmc-better-than-a-tenant-part-1-services-and-processesEven if someone give you a referral, don’t make the mistake of assuming the PMC will meet your expectations, just because they met the expectations of the referral source.We recommend you get management contracts from several PMCs and compare the services they cover and, more importantly, what they each DO NOT cover.

We don’t know any PMCs to recommend in the area mentioned, but since selecting the wrong PMC is usually more harmful than selecting a bad tenant, you might want to read our series about “How to Screen a PMC Better than a Tenant”:https://www.biggerpockets.com/member-blogs/3094/91877-how-to-screen-a-pmc-better-than-a-tenant-part-1-services-and-processesWe recommend you get management contracts from several PMCs and compare the services they cover and, more importantly, what they each DO NOT cover.