Suggestion needed as a passive investor in a flipping project

[Maurice George]

Hi flipping pros, 

My name is Maurice. Just begin my journey in the flipping business. I have about 50k sitting in the bank. I happen to know a gentleman who is a good handyman with at least 10 properties on his rental roll.  I just have a coffee with him before Christmas and I raise the issue on the flipping. He is mostly on rental but also occasionally in flipping business. He is currently pursing some deals in Oklahoma City and Tulsa (I am in Oklahoma as well) with each deal less than 100K acquisition cost.

Here is my problem. I have no experience in the real estate flipping and my job forces me to make this as a passive investment than an active one. If I join his projects, I do not think he will let me in his most lucrative deals. 

1. So, what is the best business plan/roadmap for this? 

2. Should I separate 50K into two or three deals or stay in one deal for all 50K? 

3. What is the best model in this? For example, If a property's acquisition cost is 70K and I chip in 35K and this gentleman (maybe his business partners as well) put in rest of acquisition cost and  all renovation cost. Should I only demand a percentage of total profit (like 10%) or would I simply lend the money to them?

4. I know this gentleman from a good friend of mine and he endorses this gentleman. From my past experience with this gentleman, I have some positive experience with him. What kind of protection (except contract) should I have before I wire the money? 

5. I happen to read some news about recent real estate market. It looks like real estate market is slowing down from early 2018. I am afraid that if I begin to invest now, the flipped property will be on the market late 2019. I am wondering would now be the best time in the flipping? I am worry that market will go south in extreme and forces me to sell at a loss or even stuck in a particular property for years. This is certainly not the situation I am looking for. 

Thanks for your input, 

Maurice