Help me define a few costs within the 50% rule & other newbie questions!

[Greg Baker]

Hi everyone, looking to begin in the buying and holding world in either single family units or duplexes.  I'm about 48 podcasts deep, here are a few questions I'm hoping someone can clarify for me.  If location matters, I'm considering towns/villages outside of the Rochester, NY area.  Thank you in advance:

1. When roughly calculating the 50% rule, specifically, principal and interest, do you always assume a 20% down payment?I'm curious how a conventional loan with a 5% down payment skews this rule?
2. Is there a rough percentage to use to calculate closing costs whether you are buying or selling?Does this include the cost of inspection(s)?
3. Is there a rough percentage to use to calculate insurance on say a $100,000 single family or duplex?
4. Can I purchase from a wholesaler if I plan to use conventional financing or do wholesalers only want to work with cash buyers?
5. Let's say I can save $20,000 per year and use this towards purchases.  Do you recommend I purchase one unit per year for 4 years with conventional financing using it as a 20% down payment, or save up the $80,000 and start the train of buy in cash>re-fi out, repeat with the same $80,000...
6. How will purchasing a buy and hold property or two this year, affect my families ability to finance a move in the next 2-3 years for a new primary family residence?(not looking to "house hack": standard move from starter home, to "forever" home)

Thank you again!