If I convert in going the conventional mortgage route, I would be parting with a lot of my $. 

Do you mean like conventional loan ?

There is also a building that is blighted that had been a convent and would be idle to convert, but I have been told they will not approve the usage for that neighborhood. 

Convert seller financing to a more conventional loan3.)

What are some of the pros and cons of going with hard money / private lending vs conventional for a second home/ investment, rental property??

I was able to qualify for a 5% down $250k conventional loan with 4-5 months of work experience, so if you can't get approved for FHA, check to see if you can qualify for conventional.  

This will also help me when it comes time to obtain a conventional loan(if that's the route I want to take) where Ill be asked for proof of income and I will need the funds for a down payment.

students deserve nice places to live. we aren't trying to be slumlords but i do realize that students probably have slightly lower expectations than other types of tenants, so i feel we wont need to break the bank in the level of finishing details like we did on our own home but we will provide housing that is clean and safe and attractive. also thinking we can use some creative materials and methods to make the units party-proof. maybe we get lucky and find some long term professors or grad students and don't have to do annual turnover on every unit. even so, i budgeted 8% for property management after watching david greene's webinar yesterday.the heloc would allow for an easy down payment and a nice buffer for rehab, and i have 750+ credit score and good wage earning history, so i think a conventional loan should not be a problem to obtain. a cash out refi might be an option on the horizon if we decide to really crank a proper rehab but the units (from the pictures i saw) are livable as-is.should i be more specific here on the address/market to get better help?

SFH with ADU will not be valued via an income approach if the buyer is using conventional financing.My view is that Bay Ho likely does not have enough ADU comps and an ADU addition will not add as much as a hands off ADU garage conversion addition. 

We got approved for a conventional loan but don't have the 20% down we need for an investment property.