I hope you are asking two separate unrelated questions, because there's no point in doing cost segregation for properties held inside your self-directed solo 401k, save for some very rare exceptions.Some of the Bigger Pockets experts who operate reputable costs segregation companies are @Bernard Reisz, @Yonah Weiss and @Julio GonzalezSome of the Bigger Pockets experts who offer Solo 401k administrator services are @Dmitriy Fomichenko, again @Bernard Reisz and @Brian EastmanReach out to them and see if they can help.

Do i t to build your online presence, reputation and credibility as a business.

With that said can anyone suggest reputable lenders that are able to assist me with a debt consolidation loan of ~25K?  

If the company is reputable, I don't need to vet the company.

A broker who can also deliver a reputable management company (themselves or an independent company) willing to take over management at closing is a real plus for any residential rental investment. 

I know it can depend on factors like the borrower’s credit, payment history, and loan terms, but I’m looking for general guidance or ballpark percentages based on your experience.Top Buyers/Companies:Who do you recommend as reputable buyers for these types of notes?

Not everyone has the same priorities - some care about interest rates the most, other care about the points the most, getting the most leverage, closing timeline, reputation, smoothness of the transaction, etc. 

Does anyone know a reputable or comp with competitive rates to set up a checkbook IRA?

I have found no record of him online aside from self-published articles made to make them seem more reputable than they are.  

They either had below mkt. rents or high vacancies and bad reputations and with super managing them I significantly grew the cash flow.