Just my two cents:
1: Those ‘We Buy Houses’ companies are in the same situation you are and as long as your fee and the purchase price works for their numbers I don’t see why not.
2. I have never used transactional lending, but my understanding it’s more of a short term hard money loan. That’s something you should be able to work out with them prior to finding a deal to learn their terms/conditions.
3. Typically when I talk to the sellers regarding this I let them know that I fully intend on adding this property to my portfolio (it truly is my intention every time), however if I see that the property doesn’t become a good fit then I have connections to many of the investors in the area and that it would definitely fit into one of their portfolios. You can stress that that is one benefit to working with you is you have the many connections that others may not. And bottom line is if they are motivated then they want out, and it only makes sense that they get a price that will secure them and you making a profit is understandable.
Hope this helps!