I have 3 newbie questions

[Cindy Shiblie]

Hi all, I'm a newbie to Bigger Pockets and have 3 questions that came out of the 90 day challenge webinar. Here they are:

-How can I estimate reno costs if I don't have a clue on prices and I don't bring in a contractor until after I buy the home? I'm so afraid to underestimate costs.

-If you do a long term rental, how do you pay back the hard money lender/private lender (if you use one)? I understand for a flip they will get a percentage of the profit, but I'm not sure how they benefit from a buy and hold. If they get a percentage of the monthly cash flow, won't that cut too much into my profit?

-What's a good monthly passive income when calculating a deal? For example, is $150/month enough to be worth it with potential maintenance costs? $200? $300? 

I appreciate all of your help and wisdom!