It depends on a few factors...

For example, if they're going to be able to cover 75% of the entire value of the next property, they should have a much easier time getting approved for the remaining 25%... depending on what kind of asset the new property is.

This could become the basis for taxation.There are multiple methodologies that are utilized by the tax assessor when determining a property's assessed value and which one is utilized is dependent on age, property type, region and other factors.

my budget for acquisition is $150k+in cash. my expected ROI I guess depends on ARV of the property, how much rehab it will need and weather I decide to flip it or hold it. 

But I began this reply with IF, because if they are all cash-flow positive, I would personally not seek to pay any of them off early (depending on your age), and instead save that money to put towards obtaining additional properties.

It really depends how hard you are willing to work.

Just remember not everyone can get a 3% mortgage and mortgages are pooled in tens of thousands with varying risk profiles. 

I would definitely be willing to join to have a dependable and experienced Super / Jack-of-all-Tradesman who would handle one-off tenant requests.

There may be several options for remediation depending on the state and applicable regulatory context.

It would depend on the price.