Many OOS investors set themselves up for failure because they don't invest the time to ACTUALLY understand:1) The Class of the NEIGHBORHOOD they are buying in - which is relative to the overall area.2) The Class of the PROPERTY they are buying - which is relative to the overall area.3) The Class of the TENANT POOL the Neighborhood & Property will attract - which is relative to the overall area.4) The Class of the CONTRACTORS that will work on their Property, given the Neighborhood location - which is relative to the overall area.5) The Class of the PROPERTY MANAGEMENT COMPANIES (PMC) that will manage their Property, given the Neighborhood location and the Tenants it will attract - which is relative to the overall area.6) That a Class X NEIGHBORHOOD will have mostly Class X PROPERTIES, which will only attract Class X TENANTS, CONTRACTORS AND PMCs and deliver Class X RESULTS.7) That OOS property Class rankings are often different than the Class ranking of the local market they live.Class A is relatively easy to manage, can even be DIY remote managed from another state.

That's a relative term. 

Ideally we will find a (relatively) low priced market to be able to get into without putting up huge amounts of capital.

Few months ago sold for $345k + other related costs. 

Should I leave as is and cover it with a mesh cover for $2800 (really considering this), put a new liner in for 8k (not including new mechanics), or just fill it (don't know the cost on filling at this time)?

They entail organizing several real estate-related processes, such as finance, remodeling, and property management.

And, most importantly, what books do you recommend that can answer the questions above and talk about related subjects.

Talk with your tax accountant.You sell it seller finance.  2 years later she calls you and said a capex item failed and she can’t cover.  

The other two units that you yourself are not occupying have to cover mortgage payment based off of rent schedule.

As I explore new avenues to grow and achieve financial freedom, we have been drawn to the world of real estate investing.While we may be relatively new to this field, we've taken the initiative to educate ourselves by reading books, listening to podcasts, and seeking guidance from experienced investors like yourselves.