I wanted to get some opinions on bringing rents up to market value.

You can take over the seller's payments, giving you until the mortgage comes up for renewal to qualify, bring on a partner, or resell.

I would suggest looking through the SBA website for more information and always check the credentials of someone claiming to be a licensed real estate agent or broker online in the state website where they claim license.  

Offer your in-laws to bring the loan current, then to start making the payments.

Do you think there are many properties that are off MLS and websites?

You could check your county auditor's website for a property search function. 

My buddy just approached me with an offer to invest with him in buying foreclosures, he is a GC and he has done house flipping before, he wants me to invest 30K-50K of my own money and use it to get a 6 month rehab loan from a hard money lender at a little over 11% interest, after the House was finished we would split 50/50, he would also add me to his LLC that we would use for that future buy, the reason I’m thinking about investing Is bc I own my own business which will bring 200K this year in gross profits, the down side of my business is that I work 12 hour a day 5 days a week, and I feel that I’m slowly burning out.

If you set it up as a partnership, normally, the limited partners (those who bring the money) would receive their money back and a preferred return on investment of 8-10%. 

You can pull the taxes from the Parish I would think if they have a website.  

If it doesn't appraise for the asking amount, then basically I would have to bring the difference to the table, or walk from the deal, right?