The question is mostly a personal financial planning question and it depends on your preference and what balance of risk and access you'd like and would be comfortable with.

If an in-person visit is not feasible, we can easily arrange video tours to accommodate your schedule.

If you don't look at them before buying in person, you will get burned at some point and regret it.   

With comps ranging from $875K-$1M and your estimated build cost at $550K, the after-completion value gives you a significant equity cushion, making this project highly attractive to lenders.If you plan to hold and rent the property, you could refinance into a DSCR loan after construction, which bases lending on rental income rather than personal income.

Are you building for pure investment purposes or are you looking to use some of the space for personal/personal business use?

I have found that going that extra mile, like the couch covers etc and making sure the person with the disability has the easiest time visiting our place.As someone with a disability (I have a degenerative neurological disorder) and use a cane, I like to make sure folks with similar issues have a good time.

If you wanted to fund a portion of the down payment would you suggest a hard money lender, personal loan, etc.?

I personally think it is best to work with local professionals with a good track record. 

I can't just put the LLC's income directly into my joint personal tax return, right?

Conducted personal research.