The minimum down on a conventional investment property is 15%.

Many of the potential deals we run across are not suitable for conventional mortgages, you would need to pay cash or use a lender who can close quickly (hard money lender).

I am thinking a portfolio loan would be the best way to go since conventional will take too long.

I would put as little down as possible for the loan that will go conventional.

1) For a conventional loan, Yes, its pretty much the same process - DTI, Credit Score, Reserves etc.

Conventional: 4.25 - 4.75% for 70% LTVPrivate (non qm): 6.25% - 6.75% for 70% LTV

Since it's in your personal name already, I'd recommend refinancing this onto a conventional loan and you'll be sitting pretty at something like 75% LTV, a low interest rate for the next three decades.Am I following correctly here?

If you are using conventional loan or maybe some other loan product, then they will do their own bank appraisal and you may have to pay more or less than that down payment, so check with your loan officer too to make sure what you are bidding will work for them and your cash reserves or cash to close are appropriate.If you are paying cash then it doesnt matter.I think you can only bid low if you think the property is worth less, or you are the only bidder.   

I may want to purchase the SFR or multifamily I live in with a Conventional 97 or a FHA mortgage.

If not, you might just consider going 5% conventional financing and leave the equity in your current house and get a lot more cash flow monthly.